It seems as though USB 3.0 is slated to arrive early 2008.

“The present day USB 2.0 delivers a transfer speed of upto 480 Mbps, whereas USB 3.0 promises 10 times of this speed taking the transfer rate to 4.8 Gbps.
Moreover, It will be backwards-compatible with USB 2.0, which is backwards-compatible with the first USB 1.1 definition.”

[SOURCE]