Faster Wi-Fi for the 360.
A new Microsoft Wi-Fi adapter is coming for the Xbox 360. This, of course, is an add-on accessory for the console as it is the only current generation runner without built-in wireless.
The version spied at the FCC includes two antennas, perhaps opening up for dual-band possibilities with the high-end Wireless-N routers.
One advantage of going with 802.11n is the increased range, leading to stronger signals for Halo trash-talking even if you're far from the router.