I don't know what a credible leak is, but it is pretty clear that they will be replacing the 20D in the least. Supplies in stores are low, and no new inventory is coming in. Some pretty credible photos of the replacement 35D have been circulating. Specifications on the new camera have been much less credible, but the hope is it will top the recent Nikon D200 release and steal business from them, convince old 10D owners to finally upgrade, and of course grab upgrades from current 20D owners as well.
Of course there will be many pocket digicams released as well, and hopefully some good surprises.