Intel is paying CodeSourcery to do performance optimization work for them in GCC and right now they are tackling unaligned vector instructions for the Core 2 and Core i7 families.
CodeSourcery expects to commit their Core optimizations to GCC by the time GCC 4.6 Stage 1 is complete. This will be great news for GCC 4.6 if these optimizations are significant, but considering that GCC 4.5 was just released, we are probably about a year out from having the official GCC 4.6.0 release.
We can't wait to see the performance impact on Intel's newest CPUs once this work is complete and we'll certainly be providing benchmarks. In fact, the Phoronix Test Suite was already brought up in their discussion so we should see some nice improvements in our tests.
The CodeSourcery mailing list message announcing this work that's funded by Intel can be read on the GCC mailing list.
If you are interested in seeing how Intel's newer CPUs perform right now under Linux we have our test results from the Intel Core i3 530, Intel Core i5 750, Intel Core i7 870, and Intel Core i7 920.