Everything USB has done a nice review of the Imation USB 2.0 Micro Hard Drive 4GB.

There are heaps of hypes surrounding the Imation USB 2.0 Micro Hard Drive. First, Imation touted the miniature storage as the first USB unit to feature 0.85" HDD - the world's smallest certified by The Guiness Book of World Records. The drive also mimics the looks of a padlock, giving the product a bit more media (blog) spotlight. So, hypes aside, we will see how the Imation fares at real-life tasks. Padlock USB Drive The Imation USB 2.0 Micro Hard Drive certainly has an interesting shape; it is modeled after a padlock with a flexible USB connector acting as a clasp. The cable locks firmly into position, and you can only release it by sliding the latch. A 4" USB cable is tethered to the 1.8 oz. mini drive, and is long enough to reach any crowded USB hub or the back of an iMac. Though, none of us would mind if Imation throws in a USB extension cable at any length. Read the full review at Everything USB.