I'm sort of half and half.
All my friends know, and if I'm going to make close friends with someone, I make sure they know. But beyond that? Yeah, I'm a guy. Just a guy. On every website I'm on, the only people who know I'm trans are close friends (And on one forum, people that've known me for a long time).
Well, and the people at my bank. They know something is up with me. Last time I went in and the poor bank worker addresses me by my legal name, she looked confused as all hell. Which made me happy, because obviously I didn't look like I fit that name.
It's easy for me because I don't currently work, go to school, or anything like that. The absolute only time I *need* to use my legal name is on bank-related crap, PayPal, or when I'm getting published. So, my publisher knows I wasn't born as Nick Ransom, but he doesn't know the specifics, and doesn't seem to care. Works well enough for me. Obviously, when I've got the money and my family knows 100%, I'm getting that disgusting name wiped off as much as possible, but for now? I can deal.