Hitachi believes they can have a commercial 3.5-inch hard drive on the market that can hold 5TB by 2010. The company aims to achieve this boost in capacity with write heads that use something called current perpendicular-to-the-plane giant magnetoresistance (CPP-GMR), which pushed data density above one terabit per square inch. More on http://www.techspot.com.
Back in 1984 I was very happy with my 10mb hard disk drive. After almost 26 years I will be equally happy with my 10TB hard disk drive. On the desktop!