All of them require a tripod mounted camera to not shoot "wobble cam." The IS technology used in the lenses/sensor mounts is fine for stills photography but it is really bad for video.
To not shoot crappy video with a 5DII, you have to take a professional approach.
So if you want to shoot video and don't want to take a professional approach, get a video camera that costs around the same (or a bit more?) than the 5D series cameras.
dilbert, I'm going to disagree with you on a few points there, somewhat. the HIS system in the 100 f/2.8 L IS Macro works really well for handheld video. I'm hoping it gets introduced into more short-length lenses to give handheld shooters some more options.
rather than shelling out $3K for a video camera, you can also just buy the 5D II and then get a decent handheld stabilizer unit for about $500. anyone who learns to use a steadicam or glidecam, in conjunction with a tripod, and maybe the cheapo manfrotto 127VS dolly system, can start to make some pretty impressive amateur video.
not saying the $3K video cam isn't a bad idea, but you can do pretty well for video without having to give up your 5DII