This is the closest thing I could find:
http://www.dpreview.com/reviews/canoneos5d/page21.asp
It doesn't appear to implicate the 350D directly, though it seems to suggest it. I clearly recall seeing the 350D specifically mentioned, but cannot find that link at this time. Funnily enough, if you were to view the 350D review at DPReview, it actually shows the samples from the 350D to be brighter than those on the 20D, even at the same exposure settings. So it leaves me to wonder what the actual sensitivity of the 350D really is. If the 20D is already 1/3 stop more sensitive than usual, and the 350D is even more sensitive than that, then...do we really have an ISO 200 setting labeled at ISO 100 after all?
Still, to me, this 'improved sensitivity' is a significant advantage. If I really had to push it and take photos in dim conditions, the ISO 1600 is very helpful.