There's more to USB 3.0 than just fast storage; like Intel's Thunderbolt, it can carry video or networking data as well, with the right adapter. Thanks to some advances from DisplayLink (the underlying technology vendor) the Mac compatibility story for USB video is getting better.
Kensington has announced Mac compatibility for its line of USB 3.0 Docking Stations and its Multi-Display adapter. The adapter are using the latest DisplayLink Mac driver to provide compatibility with OS X 10.6 Snow Leopard and later when used with a MacBook Air, MacBook Pro or iMac that supports USB