Level 20 - normal ground mount
Apprentice Riding (Skill 75)
60% land mount speed (same as the current level 30 mount)
Cost: 4g training + 1g mount
Level 40 - epic ground mount
Journeyman Riding (Skill 150)
100% land mount speed (same as the current level 60 "epic" mount)
Cost: 50g training + 10g mount
Level 60 - normal flying mount
Expert Riding (Skill 225)
150% flying mount speed; 60% land mount speed (was 60% flying speed)
Note: this means that to travel at 100% land speed you'll want to get out your ground mount
Cost: 600g training (faction discounts now apply) + 50g mount
Level 70 - epic flying mount
Artisan Riding (Skill 300)
280% flying mount speed; 100% land mount speed
Cost: 5,000 gold (faction discounts now apply) + 100g mount
Cold Weather Flying remains unchanged.
Summary: You'll be able to get your first mount at 20, epic mount at 40, and your flying mount at 60, which is 10 levels earlier than the current system. Epic flying is still only available at 70, but will be cheaper now that faction discounts apply (for exalted, that's a saving of 1000g). Cold Weather Flying will not have its level or cost changed.
At present, we get our flight form at 68 (trained). Will the new system mean druids can have normal flight form at 58, to keep it in line with having it two levels earlier than other classes? Or will they simply bring our flight form in line with everyone else? Personally, I am just curious - it would be handy dandy to have flight form at 58 when you first venture into Outland, but certainly no biggie to wait two levels.
I suspect we'll see a few people complain that a mount at 20 and epic mount at 40 will make our travel form "useless" (cue cries for a replacement skill I would imagine) but I still use mine plenty, even on my high level druids.
Edit: Blizzard has now confirmed that travel form will be learned at 16, and normal flight form will be learned at 60, as 150% speed (up from 60%). Swift Flight Form remains unchanged. Thanks Treebound Cat for pointing this news out :)
The Swift Flight Form quest chain will remain - it is not being removed.
And for our non-druid friends (or non-druid alts!):
Aspect of the Cheetah: Requires level 16
Ghost Wolf: Requires level 16
Paladin Warhorse: Requires level 20
Paladin Charger: Requires level 40
Warlock Felsteed: Requires level 20
Warlock Dreadsteed: Requires level 40
I think this is fantastic news for everyone wanting to level. Being able to ride around at 20, and have an epic mount at 40 is really huge. That will speed up levelling a great deal. Suddenly the Barrens doesn't seem so bad! ..and being able to fly around Outland from the get-go - instead of waiting til you're nearly finished with the place - will be a huge help.