i don't know if the op is still checking this thread...
one HUGE law firm, with offices in London, New York, Houston, Atlanta, etc., actually has a page talking about their GLBT group and how they creative a positive environment for gay employees, etc.
I think many people erroneously clump together racial minorities and homosexual applicants, when these are undeniably two different kinds of applicants who are viewed differently by adcomms (or so I expect, and hope).
And, no, I'm sure they don't verify anybody's homosexuality. I mean, really, what are they going to do? Ask for a videotape?