Geez, I wonder if you are going to get biased answers to this question.
Anyway, that is a tough decision. IMO, the Camaro is a much better looking car on the outside. The interiors are a toss up. The performance on the 2011 Mustang is looking to be pretty damn awesome. I'd wait until you see some real performance tests from C&D, Motor Trend, etc on the Mustang and, as earlier posters said, have a test drive in both - then make the decision on what you think the best car for the $$ is.