I recorded a friend of mine with my sony ericsson k750i handy in front of a usual white housewall. then I created my node setup to key out the white color - it needed some additional tweaking by hand… but although it was complete done in Blender!
the background steems from a selfmade test-animation, which I made a few weeks ago. so the background and the “real footage” weren´t really coordinated together. 
but I think it´s a good test to show what´s possible in blender…
the link:
http://www.youtube.com/watch?v=Zos3kFCQMVU
greetz,
tom