There are actors out there who use their facebook/myspace for their friends/family and for fans as well. I have run into a couple who's profile I could just see if I wanted to because I am in the same network as they are (New York City). Keep in mind that on facebook one of the privicy settings you can set up is to have your profile be viewable only to people that are in your network. So, if you live in NYC you can see some actor's profiles without "friending" them.
I do think that Tale of Two Cities is the first show that I can think of where they put a link to the actors myspace or facebook pages.
Speaking of that show, I IM'd via facebook one of the actresses in the show and we ended up having a lovely conversation. She told me that I should IM her whenever she is on despite the fact that there are times that she told me that she would be signed on but not at her computer. When I saw her at the stage door she gave me a VERY warm hello and chatted with me for a bit. There are some actors out there who love talking to the fans.
"If you try to shag my husband while I am still alive, I will shove the art of motorcycle maintenance up your rancid little Cu**. That's a good dear"
Tom Stoppard's Rock N Roll