Shroomy
Adventurer
I'm just sad we have another DEX/WIS race on top of the Elves and Razorclaw Shifters.
Otherwise, I really like their flavor. Githzerai have appealed to me for a long time.
FWIW, I'm betting on Hobgoblins, Kobolds, and Wilden being the other three races. The last, we know. The former two are just conjecture.
-O
I think 3 of the four races have been confirmed: githzerai, wilden, and minotaur. The fourth is up for grabs but I've seen a picture of a crystalline humanoid that was taken from the recent "Design & Development" article on psionics:
http://i29.tinypic.com/21o8zdh.jpg
Some have speculated that it may be the new maenad.