With Eden Beta 3, XBMC introduced XBMCbuntu. It replaces the XBMC Live install, and basically is a ‘buntu that boots into XBMC. It lets you tinker on system level using a GUI, so you no longer need to be a terminal freak in order to set up wifi on a dedicated XBMC machine.
I always chose L/Ubuntu for such a machine, and then installed XBMC the ‘classic’ way, but that method has its disadvantages. For pros, XBMCbuntu is not that much of a leap forward, but for wannabe unix nerds like me, it makes things (a lot) easier.

More info on this on xbmc.org.

Update: Oh, neat! Now XBMC does ‘Movie Collections’, too. Finally, all the James Bond movies are kept in one place.