Sounds very exciting! Will be very interested to see what it can do, though tbh, I'm usually quite happy with pictures from my 400D, so I guess this'll be a great surprise.Looks like another 400D owner is waiting for an upgrade!
Do you have any idea what sort of time the announcement is going to be made? I'm never sure what determines which country makes the announcements of products, so can't really make a guess! I'm going to be working all night here though, so hopefully will be able to keep an eye on the news to see it
If it wasn't for the advent of DSLR video, I wouldn't have been in any great rush to change my 400D. Mine was tired from extensive use, but as you say, the images are pretty good to this day.
Going to a 7D, the thing that mattered least to me was megapixels, or high ISO particularly (still have my film head on, I see folk shooting at iso 102'500 and just think, why?... there can't be any contrast in light that dim, sometimes things are supposed to be dark) that said my 7D at 3200 is like the 400D at 800, and the 7D is outdone by my M, by at least a stop of noise.
A decent pentaprism viewfinder, better handling, off camera E-TTL flash command, and the increased buffer rates are all great reasons to upgrade. I never looked back, even although I really really enjoyed my time with the 400D.