It's here, and pretty well what most people were wishing for (and predicting I might add):
http://www.dpreview.com/previews/canoneos5dmarkiii/
1) slightly increased MP (didn't really need more),
2) better high ISO (good idea),
3) slightly faster frame shooting rate at 6 fps (it wasn't really a deal buster at 5 because it was made for landscape shooters),
4) However - it's main weakness has been fixed - hopefully - better AF system - something that many complained about in the 5DII. And this has really been changed - more features.
Actually there is a lot more, but the article covers it.
Glenn