Found this good interview with Avner Ronen, one of the founders of Boxee. Interesting to hear about Avner's previous work on XBMC and helping out the project. So far there's been two forks for XBMC, Plex and Boxee. Boxee is certainly the more interesting. I would use it more but I find XBMC does everything I need and I love the Mediastream Skin, which looks amazing on my 40inch LCD screen.