I know this is quite an old thread, but I'd like to add that I bought an Xbox Live bundle (Xbox Live Arcade games, Year of service, Headset & Xbox Live Vision camera) And I have to say, it worked just like the built-in camereas right out of the box. I have an old iBook g4 12 inch and I tried this on Tiger and Leopard and I just plug it in and it's good to go for Skype, iChat, and Photobooth. Even the silly little flash things work.
I visit this page because I'm looking for something for my mom, she's having trouble shopping for one for her Mac and I was looking for something that had a mic and a cam for her Mac mini. I might as well just give her the Xbox one, which would finally allow us to iChat across the state.
Good luck to everyone else, I looked in my local stores the camera alone (not with the bundle which was 70 USD) looked to be around 40 USD. Hope this helps someone... just don't expect it to include a mic or anything fancy. Just a focus knob.
P.S. I also tried to use the same Microsoft Xbox Live Vision camera on my Windows PC and it had to install about 3 drivers before it worked, which turned up not signed (or whatever that message pops up when you install ANYTHING) I thought that to be quite ironic and a little predictable.