My 24" iMac 2,8GHz that arrived this morning has been having freezing issues as well. Doesn't matter when, or what I'm doing at that time, the graphics just freeze but I can still move my cursor and I can hear the sounds when I'm increase/decrease the volume.
I tried updating to 1.1, didn't fix
I tried downgrading back to 1.0, didn't fix
Installed smcFanControl 2.1.2, upped it with 50% (iMac ain't that silent anymore), still not fixed
I'm crying my heart out here.. Over 8 weeks of waiting, just to get a faulty iMac.. I installed WoW, tried to play, but I didn't even get to update WoW because when I log in, it freezes. Same goes for iTunes, or about any other application (even froze when I opened the Mac Help window a minute ago).
I sure hope as hell this isn't a hardware error, else I have to send it back and wait for my new one to arrive (that will most likely have these issues too)..
Hmm, typing this post is the first time in an hour that my computer didn't freeze after 1 minute..
Bummer. At least it's new so you probably don't have any data on there. I'd wipe and reinstall OS X from scratch, then not install any updates until Apple has the issue resolved.