The Tech Report has published a roundup of four 2.5" 7200RPM laptop HDDs, you can check out the results over here.
Another similarity among these drives is the fact that they all use two platters, which seems to be the practical limit for 2.5" models aiming to slide under the 9.5-mm thickness ceiling imposed by most notebook drive bays. Despite the common platter count, we still get a range of capacities. Seagate is the only one to bring 750GB into the 7,200-RPM realm and actually have product on store shelves. Hitachi has announced a Travelstar 7K750 with similar specifications, but it's not available for sale just yet, so we're stuck with the 500GB 7K500. Western Digital's Scorpio Black line also tops out at 500GB, and that model came out later than expected, putting the company a little behind its competition. Samsung has taken an intermediate step up to 640GB.