World of Warcraft Client Patch 1.12.1
- The riding skill has been changed. A riding skill of 75 is now needed to ride level 40 mounts and a skill of 150 for level 60 mounts. Those that already have mounts will automatically be granted the appropriate level skill.
- Players will no longer lose the Silithus or Eastern Plaguelands PvP buffs after dying in the zone.
- Players will now port to the Crown Guard Tower graveyard if they die in Fungal Vale while their faction controls the tower.
- Players will no longer be interrupted while sitting down in Eastern Plaguelands when contested towers change ownership.
- Players will no longer be interrupted while sitting down in Silithus when a side collects 200 Silithyst and wins the event.
- In the Silithus World PVP event, the dust cloud graphic that appears on a flag carrier will now properly trail behind the character while running.
- Players will no longer receive honor if a tower in Eastern Plaguelands is captured while they are stealthed.
- Lordaeron's Blessing buff from Eastern Plaguelands is no longer dispellable.
- Players on Windows machines will now hear the victory music when their faction fully captures a tower in the Eastern Plaguelands.
- Players that log out of the game and back while having a pet summoned will now be properly credited a Soul Shard.
- Warlock pet sounds have now been added in all languages.
- Canceling Bloodrage while in PvP or dueling will no longer remove you from combat.
- Most enchantments on items are no longer counted against the maximum limit of effects a player can have on them, so it should be much harder for a player to exceed their max limit on effects and have one be removed involuntarily.
- Fixed a graphical error with the Dreadnaught Helmet.
- Fixed an issue in which the "Blessing of the Claw" from the 6 piece Dreamwalker set was causing players to stand up after trying to eat or drink.
- Fixed an issue where multiple armor set bonuses were not applying correctly when switching out pieces.
- Fixed an issue where the four-piece Plagueheart set was not properly applying to corruption.
- The Blade of Eternal Darkness will now only proc when damage is done.
- Fixed a graphical error with the Dreadmist mask in which it would float above the Tauren Females' head.
- Fixed a graphical error in which enchantment glows were not updating if the same item with a different enchant or no enchant was equipped.
- UI windows will now be positioned correctly if the right action bar is activated.
- When going from Windowed mode to Full-Screen mode, player names will no longer be replaced with "..."
- The Quest Tracker will now properly display purchased quest items.
- The Battle Map in Outdoor PvP and in the Battlegrounds will no longer get stuck when dragging with the cursor in windowed mode.
- The Battle Map in Alterac Valley will no longer switch off whenever a graveyard, tower, or mine changes ownership.
- Players will now be able to complete the quest,"Target: Hive'Ashi Sandstalkers".
- Fixed an issue where players could be afflicted by "Withering Touch" more than once at a time.
- The Plaguewood teleporter will now teleport players to the correct location within Naxxramas.
- Fixed an issue where players were getting the message "Invalid" when trying to select flight paths.
- Fixed an issue where if the disenchant window was forced closed, a player would lose both their reagent and the item they were disenchanting.
- Fixed an issue where players could crash while fighting Anub'Rekhan.
- Fixed an issue in which players trying to disenchant an item with a full inventory and then casting a spell afterward would lose the reagent and the item.
- Fixed an issue where weapon procs will now work with instant abilities.
- Pet buffs will now apply and remove properly.
- The Priest talent Spirit Tap will no longer sometimes proc off of totems.
- Players will no longer hear any sound when they have "Enable all Sound" turned off.
See also: FAQ posted by Hortus
Explanation of the Changes
Source:  link currently broken by search feature bug in official forums
This change was implemented after the latest revision of the patch notes was made available for inclusion into the 1.12.1 patch binary. It will be documented in a future revision however.
There will be effectively two riding skill levels, Apprentice and Journeyman. The cost for the riding skill will be significantly higher than it previously was, however this is offset by a drastically lower cost for the actual mount.
For current players with mounts there will be a seamless transition to the new system. You will continue to have your mount; you will continue to be able to use it, etc. What this change does for players who don't yet have a mount or an epic mount is take the emphasis off of the mount itself, and put it on the riding skill. This helps give players access to more variety without requiring a large monetary investment if they, for instance, just want to pick a different colored horse.
Source:  link currently broken by search feature bug in official forums
In light of the recent changes to the mounts and the surrounding hysteria therein, I have written this F.A.Q. Please feel free to correct it.
Let me say this first: After the changes in this patch, you will spend the SAME amount of money to learn to ride and buy a regular or epic mount as you did before the patch. The costs are merely reversed.
'What are the changes to the mounts and riding system?'
In a nutshell, the cost of learning to ride a mount and the cost of purchasing a mount have been swapped. Instead of paying 80g for a regular mount (undiscounted) and 20g (undiscounted) to learn riding for that mount, you will pay 20g for a regular mount and 80g to learn the riding skill. Instead of paying 1000g for an epic mount (undiscounted), you will pay 100g (undiscounted) for the epic mount and 1000g (undiscounted) for the riding skill.
'When will this come out?'
Patch 1.12.1. Not the expansion.
'What is the current state of riding skill?'
Currently, there are various types of riding skill, one for each type of mount. Riding (Wolf), Riding (Nightsaber), and Riding (Ram) are each separate skills that allow you to ride an Orcish Wolf, a Night Elven Nightsaber, and a Dwarven Ram respectively.
You cannot learn the riding skill of another race or buy that races’s mount unless you are exalted with that race. This is how Blizzard restricted cross-racial mounts. Therefore, in theory under the current system, an Orc could own a Swift Orange Raptor*, but would be unable to ride it unless that Orc had Riding (Raptor).
'But I thought you said that you could only purchase cross-race mounts if you were exalted?'
Correct. However, all standard mounts (non-PvP, non-drop) are BoU, or Bind on Use. They are not BoP. Under this system, an Orc could give his Troll friend 1000g (undiscounted), the Troll would buy the mount, and then trade that mount back to the Orc.
This was especially helpful for non-PvPers or those who were not yet honored with their own race. A non-honored, non-PvPing Human would spend 80g on his mount, while an honored human of rank 3 or above would spend 64g because of the two 10% discounts.
'How does this change in the patch?'
In the patch, there will be only two riding skills, presumably one for the Alliance and one for the Horde. Purchasing that riding skill will allow you to ride all mounts of that faction, regardless of their race.
However, there will now be two levels of riding. Apprentice riding will cost 80g (undiscounted) and allow you to ride regular mounts. Journeyman riding will cost 900g (undiscounted) and allow you to ride epic mounts.
'I already have my regular/epic mount and I know how to ride it. What happens to me?'
Blizzard has suggested that you are going to be transitioned over with no additional cost. If you have an epic mount and can ride it, you will not need to spend extra money to relearn it. If you have a regular mount and can ride it, you will not need to spend extra money to relearn it.
'I have a PvP mount. What happens to me?'
This is somewhat less clear. According to Hortus,
Rank 11 mounts, and the AV faction mounts should only require apprentice level riding skill.
If you choose to PvP up to rank 11 or to exalted with AV and get the mount, you will not need to purchase Journeyman Riding for 900g (undiscounted). You will only need to buy the mount and have Apprentice Riding for 80g (undiscounted). I am unsure at this time if the price of these mounts will drop.
'I have a special mount, such as the ZG raptor or tiger. What happens to me?'
Again, this is somewhat unclear. Presumably, because of the special nature of the mount, it will be treated like the PvP/AV mounts and only require the Apprentice Riding skill.
'I am a Paladin or Warlock. What happens to me?'
Edit: I have been told that on the test realms, paladins and warlocks are being given Journeyman Riding if they already have their Epic Charger or Epic Dreadsteed. However, it is uncertain whether completing your paladin or warlock mount quest after patch 1.12.1 will cause you to automatically learn Journeyman Riding.
We shall see.
'Who does this hurt?'
If you have already purchased your mount, but are too low of a level to ride it when the patch comes through, you will be paying 2x what you would normally. Example: my 37 druid has her mount already, but is too low to use it. If I do not level her to 40 by this patch, I will be forced to pay another 72g (honored, no PvP discount) to learn to ride it.
'Who does this help?'
Anyone who wants a mount of a different color. If you’re sick of your Frostsaber, you can spend 100g (undiscounted) to buy a Mistsaber. Potentially PvPers, who will spend less overall.
In addition, if you already have gotten the reputation for a cross race epic mount, but have not yet bought one AND you already have your same-race epic mount, your new cross-race epic mount will only cost you 100g (undiscounted) instead of 1000g (undiscounted). This is good!
'What about cross-race mounts'
At the moment, as I described above, standard mounts are BoU. The limiting factor in cross-race mounts was the riding skill.
In the new system, mounts are BoP. You will only be able to purchase a cross-faction mount if you have the correct reputation with that race. The limiting factor in cross-race mounts will now be the mount itself.
'What about selling cross-faction in the neutral AH. Trolls on Rams?'
Now that mounts are BoP, they cannot be sold on the AH. In addition, all mounts have racial restrictions on them. The tooltip for Mechanostriders, for example, says only Dwarves and Gnomes can ride them. Therefore, even if you could get a mount cross-faction, you couldn't use it.
Cynical view: someone at Blizzard chose the wrong color Kodo and was too lazy to spend 800g on a new one.
Less-cynical view: Flying mounts in the expansion will probably require a different riding skill and be unifactional. This resolves that problem.