Check out this new article Wizards of the Coast posted recently:

Ask Wizards: 11/03/2006

Q: I have a question concerning the race of drow. Why does it cost them 3000 XP to level up, when it only costs a moon or sun elf roughly 1000 XP? More importantly, if there is a reason for this expensive experience cost, what is it -- does the drow get more perks and advantages in the beginning or later on?