Room there for SSD to bring it back up to 9.5mm
You suggest they will take the speed up to 7200rpm, and the size up to 320GB. For me, it would be far more interesting to get a normal-sized (9.5mm thick 2.5 inch) drive with, say, 80GB of MLC SSD (for OS and apps) and 250GB of 5400rpm HDD (for documents). That would give my laptop (early 2007 MacBook Pro, 2.16GHz Core 2 Duo, 3GB RAM, 160GB disk) a new lease on life!