Seems like Seagate is trying to make up for some lost time in the storage technology field. After a late entry into the SSD market, Seagate may be getting a jump start on the ultra-thin drive market. One of the issues with the new ultra-thin generation of notebook computers is the hard drive size. You can only make a computer so thin before you run into issues with the thickness of the components.
Currently drives are either 9.5 millimeters for a laptop, or 12.5 millimeters in the more traditional desktop drive. The thicker drives normally come in larger capacities, because they allow for more platters. Seagate has been working on improvements in magnetic storage techniques, which has reduced the need for multiple platters.
Seagate has been mum about the capacities that the new drives will come in, as well as keeping the pricing quiet. The official announcement is expected to come on January 5th.