According to a report from Dean Takahashi, Microsoft maybe ready to roll out 360's with the 65nm chipset and motherboard this fall.
The article goes on to say that this summer they are in the process of qualifying the new codenamed "Falcon" chips and motherboard.
"Falcon is the name for the latest internal electronics in the Xbox 360. It will have an IBM microprocessor and an AMD/ATI graphics chip that are manufactured in a 65-nanometer production process. These are cost-reduced chips that do the same thing as their 90-nanometer predecessors, but they’re smaller."
This would be a welcome change, that would provide less heat and even possibly move the "Gigantor Power Brick" to inside of the revamped 360's.
Check out the full details of Dean' story here: Story Link