After reading the news that Microsoft had flown the 65nm refresh of the Xbox 360 under our radar, I pinged its local PR to get some more info.
I received a response today but, as usual, it's about as meaty as a piece of KFC:
"We are constantly updating internal components on our consoles and therefore will not comment on details of specific components or manufacturing processes."
Essentially, as far as Microsoft is concerned, they don't mind what goes inside its consoles, as long as they work. This, of course, means we're not going to get any guarantees on which units are based on the newer hardware, or if there's a future SKU waiting in the wings that'll definitely have 65nm parts.
And just to fuel the Halo 3 DLC rumours, I have it on good authority that Bungie is "working on it". But you already knew that (Thanks Luke for the link).