GeForce 9800 GTX+ features a 55nm chip
Handfuls of pictures are also included in the link above.
By my crude measurements, the 55nm die is 15.2mm high, or 231 mm^2 in comparison to the 65nm G92’s die area of 324mm^2 – a savings of approximately 40%.
So that seems pretty complete for a pictorial guideline, right? The real question you might be asking is why would NVIDIA NOT want to push the point home about the 9800 GTX+ being a 55nm part? Obviously there are some advantages to it: lower power, less heat, faster clocks (obviously).
My guess is that the marketing team at Big Green didn’t want to one-up the recently released GT200 parts – some people might assume that singe it was built on the 65nm process while the new 9800 GTX+ is on the 55nm, that the GT200 would be inferior in some way. As we saw in our performance review of the GeForce GTX 280/260 cards, that’s obviously not the case but I can see how some readers might make that conclusion. 
