An enterprising hacker by the name of Sarah Sharp has posted a USB 3.0 driver for Linux that'll be making its way into the next revision of the operating system.
The driver is available now, but given the near-total lack of USB 3.0 devices so far, you won't be able to do much with it yet. The new standard can, however, achieve real-world transfer rates of 500Mbps, compared with 25Mbps in USB 2.0, the current standard.
USB 3.0 is targeted initially at PCs, Blu-ray players, hard drives, flash card readers, and optical drives. It'll be backwards-compatible with USB 2.0, which is itself backwards-compatible with USB 1.0, so don't worry about your old devices not working any more. You should be fine.
Linux 2.6.31 will support the driver when it's released in September, says Sharp.