http://www.urticator.net/essay/0/48.html
Might be a useful read apropos of Wei Dai's recent question:
Why are we causing [people] to think of LW in terms of identity in the first place, instead of, say, a place to learn about and discuss some interesting ideas?
So maybe this should be the last bias one overcomes then :)
In any case, this particular link doesn't deal with identity itself, just a potential negative side effect.