A post from WoW Insider discussed the idea of a "leveling server". A server where folks would go to level their toon then upon hitting 80 would move to another server. I think it's an awesome idea for several reasons.
Firstly, many of us end up leveling alone, which can make leveling kinda lonely. It can also be difficult to get groups together for group quests. Often you'll end up calling upon an 80 from your guild to come kill a mob for you. What about all those great low level instances? You can never get a group for your level to do them. I think that they are an important part of the game to get to know your class and understand teamwork in the game. People level to 80 sometimes never seeing these great instances.
Unfortunately from the article "A leveling server, just for leveling" WoW insider is pretty certain that Blizzard wouldn't be interested in such an idea. On a social level alone I think it would be worth it.
Speed leveling is nice but there is something to be said about really seeing the game and all it has to offer.