Found htis out in the first day of CoD4, obviously not the the multitude that he has. You don't even need to jump when you land, you just bounce off. On maps like crash where there are little concrete barriers you can just run along, jump and land on top of those, you still jump quite a ways.
edit: oh it's called overbouncing, and its not new, its oldschool q3 engine shit, it was possible in CoD2 too but not to such an extreme
I'm guessing that will be fixed in 1.3 or 1.4...?