360 Insider have reported:
"Xbox Live might be “free” this generation, but not if you want to do some multiplayer gaming. You still need to shell out the $50 a year (which, in my opinion, is more than worth it). As with the old Xbox, XLink Kai(http://www.teamxlink.co.uk/) is to the rescue.
Today, before the new console has even launched, it has been announced that XLink Kai now officially supports Xbox 360. That means games with system link mode are able to tunnel through the internet and hook up with other XLink Kai users to do what system link was never meant for–online play.
With services like XLink you miss out on a lot of the ease of use and simple integration you get with Xbox Live, so I really recommend going for Live Gold if you can swing it. Free alternatives are always welcome though."