Reprinted from a Western Digital press release:

Western Digital® today announced that it has commenced volume shipments of its 9.5 mm high, 2.5-inch notebook hard drive with 640 GB capacity. The WD Scorpio® Blue(TM) 640 GB hard drives utilize 320 GB-per-platter technology and are designed for mainstream notebook computers. The WD Scorpio Blue 640 GB is the highest capacity 2.5-inch hard drive available today in the industry-standard 9.5 mm, 2-disk form factor.
The new WD Scorpio Blue 640 GB drive has a 30 percent reduction in overall power consumption from the previous generation WD Scorpio Blue drive to achieve best-in-class power and performance(1), making it an ideal solution for notebook computers and other portable devices that require extended battery life and cool, quiet operation. Read the rest of this entry »