Xbox 360 Wireless N Networking Adapter out this week in North America [update]
The Wireless Adapter N adds support for the 802.11n protocol, which should allow for higher-speed wireless connections. It also adds a second antenna, which allows for symmetry. Given its high price, it may cause buyers to suffer like the 802.11g did.
Update: We've confirmed with Microsoft that the original 802.11b/g adapter will only be available while supplies last — at a new price of $80.