The demo for C&C3 is out. I was playing it earlier this afternoon. I really enjoyed it. It seems like pretty standard RTS stuff so far, but it is visually very attractive.
Personally I loved the FMV stuff. Of course it was made even better for me by Michael Ironside (Starship Troopers), Cameron (House), Sawyer (Lost) and Boomer and Number Six (Battlestar Galactica).
I still haven’t tried Supreme Commander. I’ll download the demo for that, as everyone is talking about it. I suck at RTS’ though. I love them, I just haven’t been very good at any of them since my Starcraft days, so all Supreme Commander sounds like to me is a chance to lose on a grander scale with prettier graphics.