I just received my new passport. In order to get it, I mailed my old passport, two pictures, the application (from the 'net), a check, and notarized copies of my name-change and surgeon's letters. I got the new passport in less than three weeks. I did not ask for expedited service. A couple of days later I got the old passport and the name-change and gender-change letters back.
My old passport was still valid, which I'm sure helped a lot.
- Kate