The 20GB and 30GB models measure 0.2 inches in height and weigh 1.7 ounces. The 40GB and 60GB ones are 0.3 inches high and weigh 2.1 ounces.
"The new form factor compliments our current line up of 1.8-inch drives whilst helping our customers deliver innovation, in terms of size and performance, for next generation feature reach devices."Toshiba has already produced more than 14 million 1.8-inch hard drives. Soon they will also launch 1.8-inch HDDs with perpendicular recording, to reach 80GB capacities.
Source: Yahoo