I haven't gone back to the SSA yet to do my gender change. When I did go in for my name change, about 3 months ago, I had a letter from my SRS surgeon stating that I was scheduled for SRS surgery in January 2010 (used this for my temp passport gender marker change). But, being me, I thought I would produce this letter to attempt the gender change whilst doing the name change to save a later trip ..... It didn't work, they did need what Janet describes, "irreversible genitalia surgery". Even smiling pretty didn't work.
None of that is really helpful or news, but to back Nero's assertion of not liking to do these things in public, I had a bit of an experience at the SSA office in Indianapolis I went to. The clerk was completely baffled and confused by what I was asking for, and it took her 3 trips back and forth with her supervisor, he coming over finally to fulfill my name change request. By then, it pretty much had the attention of the entire waiting area, of about 35 people. So much for privacy. And to top off the situation, at one point, the clerk, when talking to her supervisor, and within my hearing, actually referred to me as "it". So much for sensitivity.
I ended up calling her out on that, asking her directly why she had referred to me as "it", and she apologized profusely, and when I told her she needed sensitivity training in a cold flat voice, she vehemently said she didn't, halfway on her way to tears ... no winners in that situation.
Good luck with the SSA! I'm headed back to the SSA on my next visit to the US in a couple months with my letter for gender change, hoping that it's a bit smoother this time.
Melan