From: Essex, England
MS are releasing an application filter for it, the internet enabled games use stupid port connections (mainly because MS believe multiple people will be playing from behind 1 router/firewall, and they are suffering from the directx "1 person behind a firewall only" problem right now).
From: Seattle, WA
At this time XBox does not support any online play. There are games however like Halo which support multiplayer through a LAN only. I'm sure much more info will come around as soon as all the online stuff starts coming around.