Boy Nick you got good eyes! Did you figure out what HD just by the presentation and Apple web site info? Assuming that is correct:
Looking at the Hitachi web site Hitachi TravelStar HD's All of their current drives are SATA III (6GB/s) so it's likely the custom Apple HD Hitachi makes is a SATA III. Beyond that it's anyones guess until iFixIt does a tear down or someone does a guide for it.