I am waitlisted at UCLA, deferred at Columbia, Cornell, and Northwestern. (Who knows, there could be more waitlists in the mail, too!) I looked at LSN and it looks like most people got accepted off the waitlists/deferrals in june or july, some in may, and few in april.
It's really aggravating, especially since I'm trying to time my grad school attendance with my husband's! So I don't know if I'll be able to wait long enough to find out either way . . . but I don't want to look back and regret not waiting, either!