Kicking things off with C-Ray, a Phoronix benchmark favorite, switching to the in-development GCC 4.7 speeds things up greatly. Again, same tuning options and build parameters of the test profile and the compiler itself (the compilers were built from the stock Ubuntu Oneiric GCC 4.6 compiler). This very multi-threaded friendly ray-tracing program is significantly faster with GCC 4.7 over the current stable GCC 4.6.2 release.
The single-threaded POV-Ray benchmark also sees a small performance improvement when moving to GCC 4.7, but it is not a big of an improvement as the multi-threaded C-Ray.
The VP8 and x264 test profiles don't see much of an improvement in moving over to GCC 4.7, albeit each of them already rely upon a fair amount of hand-written Assembly.