A couple people asked if they need to upgrade if they are running rc1: no, I wouldn't bother.
The only significant code change is better handling of the rare case of one of the leveldb database files being corrupted. If you're really curious, github will show you the differences between any two versions; here are the rc1 to 0.8.0 final release differences: https://github.com/bitcoin/bitcoin/compare/v0.8.0rc1...v0.8.0