From gamespot.com:

After word about Microsoft's upcoming Wireless Adapter for the Xbox got out by way of the FCC, Microsoft today solidified details about the device and set its release date.

Codeveloped by Microsoft Broadband Networking, the first-party wireless device enables users to connect to the Xbox Live service through an existing 802.11g or 802.11b Wi-Fi network. According to Microsoft, an interface on the Xbox dashboard will offer a simple setup to configure the device and security features (including Wired Equivalent Privacy, or WEP, security). With an 802.11g network, says Microsoft, Xbox Live players will see speeds up to 54Mbps, or five times that of a typical 802.11b Wi-Fi network, which can improve gaming and communication.

The Xbox Wireless Adaptor is scheduled for release on October 5 for an estimated price of $139 in the US. According to Microsoft, the Xbox Wireless Adaptor MN-740 is one of five products in the "Wireless G" product line, which is designed to simplify the sharing of a lone broadband connection between multiple devices, including desktops and laptops.