Silex Technology America shows USB 2.0 server with Wi-Fi network connection: The idea is that you could share USB 1.x and 2.0 devices over a Wi-Fi network such as printers, hard drives, and scanners. The press release mentions 802.11g and not Wi-Fi, so it's likely not certified (yet). The suggested price is $149, and it features WEP and WPA Personal support for Windows XP and 2000. It's available now.
Keyspan released an Ethernet-based USB 2.0 sharing peripheral in April 2004 for $130 which it says is Wi-Fi compatible, but would require a bridge of some kind.