I recently hooked up my X-box using a wireless adapter (yeah, those $99 have been keeping me off it for a long time!). I started getting the following message in my Linux box logs:

May  9 13:25:51 svn kernel: 10.0.x.y sent an invalid ICMP error to a broadcast.
May  9 13:25:51 svn kernel: 10.0.x.y sent an invalid ICMP error to a broadcast.
May  9 21:50:44 svn kernel: 10.0.x.y sent an invalid ICMP error to a broadcast.
May  9 21:50:44 svn kernel: 10.0.x.y sent an invalid ICMP error to a broadcast.
    
I'm pretty sure it's the X-box that sends these bogus packets, and only when it's on. Googling on the web finds that you can turn these messages off by setting /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses to 1 (you can put this into your /etc/rc.local for example).

Another thing I notice is that the X-box Live voice chat is weird. You're playing some game, where some players are far away and others are very close, but all speakers are right there in your ear on the voice chat. This breaks immersion of the game, although it brings the players closer -- it makes the experience more of a game, and less of a simulation. Don't know if I like it yet.

As an alternative, I really like what we did in There: making voice chat be based on the avatar in the world. When you're close to an avatar, you hear that avatar (localized); when you're far away, you don't. It accomplishes something different: encouraging immersion on the level of the simulation, rather than involvement on the meta-level of game players.