Most MBP displays are supplied by Apple as sealed units, and only to authorised service providers who are contractually obliged to fit any such parts they sell.
I actually can't find any MBP iSights on the parts list, though they are available from MacBooks.

As for your question, the MBP screen is not exactly the same size as the PB (15.4" v. 15.2"). I tried a 17" MBP panel on a PB/ It worked very briefly, then stopped. You might be able to find an iSight from an MBP if you ask a service centre. They might have a cracked display going spare. If the display housing is also damaged, it is largely worthless (except the camera could be intact).