The worst kept secret in history is no longer a secret. The replacement of the Canon 40D is the 50D and will be announced for release at Photokina.
Canon made a blip this weekend when it left the 50D website development outside their normal password protected area.
I have details on my blog which you can access BY CLICKING HERE
There are links to the site and the images are available so you can read the EXIF for yourself.