Mount costs, level requirements, and speed changes
Blizzard has made major changes to when you can buy your mounts, and how much they cost when you do. All of the mounts nowl have their level requirements reduced: Regular land mounts will now train at level 20, epic land mounts are trainable at level 40, regular flying mounts can be trained at level 60, and epic flying can now be trained at level 70. This means that you'll be riding at an epic speed from level 40, and you'll be able to train flying mounts at level 60 (so you'll be able to ride around Outland with a flying mount from the first time you step in there. Here are the full details on all of the riding skills and their new costs.
Apprentice Riding (Skill 75)
60% land mount speed Requires level 20 Cost: 4 gold Mount cost: 1 gold Mail will be sent to players at level 20 guiding them to the riding trainer Journeyman Riding (Skill 150)
100% land mount speed Requires level 40 Cost: 50 gold Mount cost: 10 gold Mail will be sent to players at level 40 guiding them back to the riding trainer Expert Riding (Skill 225)
150% flying mount speed; 60% land mount speed Requires level 60 Cost: 600 gold (faction discounts now apply) Mount Cost: 50 gold Can now be learned in Honor Hold (Alliance) or Thrallmar (Horde) Artisan Riding (Skill 300)
280% flying mount speed; 100% land mount speed Requires level 70 Cost: 5,000 gold (faction discounts now apply) Mount Cost: 100 gold
Cold Weather Flying will remain unchanged, so you will still have to have your first character get to level 77 before training to fly in Northrend. However, the Tome of Cold Weather Flying will be able to be purchased at level 80, and will allow your alts, level 68 or higher on the same server and faction, to fly around Northrend as they level up. So you'll only have to level through Northrend on foot once.
Travel abilities for various classes (the Druid, Shaman, and Hunter travel forms, as well as the Paladin and Warlock mounts) have also had their stats adjusted. The various spells will be available at level 16, and the mounts will match regular mounts above in speed and level requirements.
As you can see, Blizzard has majorly streamlined travel time by mount. Additionally, they've lowered the casting time on both flying and ground mounts, from 3 seconds to 1.5 seconds. So it'll take you less time to get moving as well.