USB 3.0 adoption's been slow in a very chicken-and-egg way. Manufacturers don't want to increase costs without consumer interest, and there's little consumer interest without computers being able to use it. Iomega's solving the consumer half of the problem.
Starting in early October, Iomega's transitioning their eGo line of portable hard drives (500GB and 1TB sizes) to USB 3.0, and they're charging the same price as their USB 2.0 versions. The MSRP on both will be $114 and $189, but that's MSRP, and you can find them online for less.
These portable drives will have AES256-bit hardware encryption (encryption's for Windows machines only), as well as a 7-foot drop spec and a couple bundled backup software suites they give to you for free.
They're also transitioning their Prestige Compact line in 2011 and the rest of the external, portable hard drives afterwards.
Since prices are exactly the same for the USB 3.0 version as they are for the USB 2.0 ones, you should logically get the USB 3.0 versions for future-proofing yourself. Chances are your next laptop purchase (maybe not if your next one is a Mac, since they're sometimes slow to adopt other people's tech) should have USB 3.0.
HEY MANUFACTURERS, PUT USB 3 IN YOUR COMPUTERS ALREADY!