Participants also get $5 towards the purchase of this fall's new expansion (assuming they upgrade to a paying account) and a bunch of in-game items including a pet drake, a 12-slot bag, and a bag of XP potions. Word on the street is that the previous iteration of the Living Legacy program was a big success, so SOE is probably trying to keep the ball rolling.
Note, though, that this isn't being offered to current EverQuest subscribers, just lapsed ones. Apparently SOE doesn't want to lose current EQ players to EQ2, but if you're playing neither right now, it wants you to play the more modern one. Makes sense.