According to the World of Warcraft PTR Patch Notes, players will be able to buy and use mounts at level 30.  While many people in the WoW community will compain as usual, I see this as a big plus for the game going forward.

Leveling a character in this day and age can still be a pain, regardless of the faster leveling curve.  Sure, you get more experience points now and can blow thru the pre-TBC content quicker, but the biggest problem is still having to do it on foot until level 40.  Reducing the level requirement to 30 will help players travel thru some of the larger zones in main-world WoW, including Stranglethorn Vale and Duskwallow Marsh.