It looks like the Xbox 360 processor is going to go through a change sometime over the next year that will bring it to the new 65nm process. This means the Xbox 360 CPU will be able to run software faster than the existing 90nm versions.
Thankfully, I doubt Microsoft will change the software to take advantage of the changes, because it could cause compatibility issues with games that were developed for the current CPU, and it will make many current owners, including myself very unhappy.
via VNUnet