I've been plagued by this issue for the longest time with my 7D...still haven't found an answer yet
I'm getting ready to send it to canon, as nothing I do seems to help.
I've calibrated every single one of my lenses with it, and no matter what, I end up with soft images. My wife shoots with a 60d, and the same lenses, and her pictures come out sharp. We've swapped camera's, raised shutter speeds, tried different focus points and nothing seems to help.
We've even tried removing both batteries for 30hrs, that didnt seem to work either.
When I first got the camera, pictures were sharp, but it seems to be getting worse as time goes on. However, I just picked up another 7D+17-55, so I'll have that to compare directly. Ill post up results in a few days/weeks if I remember