Externally, Seagate hasn't altered 7200.11 from the 1TB to the 1.5TB. The Barracuda is still a shiny 3.5" wide metal box with a 3GB/s Serial ATA interface. That much hasn't changed, but the engineers at Seagate had an entire year to work on performance.

The SATA interface is probably the greatest technological advancement in hard drives ever, but I believe the newer SAS (Serial Attached SCSI) interface, currently reserved for high end work stations and servers, will eventually find it's way into the mainstream market, although that may be a few years away.