Here’s a quick chart to illustrate the different sensor sizes for some popular DSLR’s and video cameras. Points of interest:
GH1 and 7D are sort of near to what you would get to 35mm film in (movie) film camera.
Canon 5D Mk II is the same as a 35mm stills camera – therefore very shallow depth of field (but also a little bit uncontrollable for video without care!)
EX1 is tiny – but then you should remember there are three sensors in the camera one for RGB so no bayer filtering required and other advantages.