Cinema Lenses?
 

Can you use cinema lenses on the 7D? If so, is there an adaptor for a PL mount to Canon available?

Yes, with the 7D sensor close to the 35mm movie frame (smaller than actual 35mm stills frame size), there are quite a few trying out cinema lenses, such as the Panovision etc on the 7D using an adapter.

Canon 7D fitted with an enormous Panavision cinema lens on Flickr - Photo Sharing!