Microsoft Could Be Prepping XBox 360 Refresh
Image by Kotaku.com
Above we have the leaked photo, below we have the XBox 360 motherboard as its more-or-less appeared to date.
The major difference between the two is the position of the GPU. We've known Microsoft was working on a combined-package for the CPU+GPU for awhile; the jump appears to have substantially cut the necessary motherboard size. Note that this marriage of CPU and GPU is often inaccurately referred to as 'on-die.' IBM has almost certainly opted for an 'on-package' approach in which distinct physical chips sit side by side. This is the same approach Intel currently uses for its Core i3/i5 processors.
There's always the risk that bringing the two parts closer together could create heat problems (again), but the chances of that happening are small. Both the Xenon CPU and ATI's Xenos GPU will be built on a 45nm process and will consequently generate much less heat than the original XBox 360, in which both parts were built on 90nm technology. Unit power consumption (and fan noise) should both drop as well, but it's too early to predict how much.
It's possible that we'll see a new XBox Slim debut simultaneously with Project Natal when Microsoft launches it later this year.