I took some photos at a dance performance:
http://home.flash.net/~brownt/a1/
They were taken at ISO 800 and yes, they're noisey. I included versions processed with Noise Ninja.
Yes, I'm know that a DSLR would have taken better photos, but I was standing less than 5 feet from the audience and the sound of mirror slap would have been obnoxious. I asked an audience member if they could hear the camera during quiet passages and they couldn't. As it was the stage manager said he was wondering if I was really taking photos or just waiting for the magic moment that never came.
I took about 330 photos in 45 minutes on each of two nights. I was limited by my 3 256MB CF cards. The li-ion battery lasted the whole performance each night. Didn't need to use the spare.