I've been pushing forward on my Paladin lately, and so I've entered the wacky world of Heirlooms. I have already picked up the leather Heirloom shoulders (thinking that even though the Pally wears plate, if I ever want to level a Druid or Rogue, I'll have them), and I'm well on my way to grabbing the new Heirloom chestpiece as well -- 20% bonus XP, combined with a healthy amount of rested XP, should make the leveling curve as easy as it gets (RaF is nice too, I guess, but I'd rather not pay for a second account). So I'm in Heirlooms up to my neck (at least until they give us helms), and I was intrigued by this question over on the Rawrcast forums: do you think Blizzard will eventually provide Heirloom items for every slot?
20% is already a significant bonus to killing and questing XP, and rested technically provides a 50% bonus. But with ten Heirlooms in 10 slots (we'll leave out weapons, since those don't have the 10% XP bonus, as well as shirts and tabards, and rings and trinkets for now), you're looking at a 100% XP bonus even without Rest. The current average 80 probably spent about 14 days leveling up, so with an extra 100% bonus, you're looking at seven days /played, or very close to the current record. At that point, Blizzard might as well let us grant levels to each other.