As far as I'm aware you still cannot get 1tb internal hard drives that will fit inside the PS3 as they're all 1 inch too big.
I've been on the lookout myself for ages.....I did see one on the CEX website that stated 2.5 inch 1tb internal hdd...but knowing CEX as unprofessional retards I wouldn't put any stock in that because it was likely a typo.
Currently the biggest hdd you can get to fit inside a PS3 *I think* is 500gb....
1TB does fit and work but you can either mod the cage by pounding down the raised bumps on the cage under the drive or use no cage and put some card/foam behind the drive to wedge it in.
Also from reading other posts elsewhere, it seem the larger WD scorpio's have a tendency to skip during cut scenes/fmv.