Yup. It's official.
What I find interesting here is that if Xbox 2 is running on ATI hardware and so will the next Nintendo home console... and when you think about it it seems like what these three consoles are going to be using is a "next" or "next next" generation gpu from ATI or Nvidia, the hardwares may not be all that different.
So other components of the machine become the differentiator, hardware wise, more than the graphics, which have been traditionally a big differentiator (compare say Genny vs SNES, PS1 vs Saturn, etc).
I wouldn't be surprised Nintendo would be the one to put forward a particular more obvious difference in their console...