XLink is a framework that allows local multiplayer gaming devices like the PSP, XBox, and Nintendo DS to emulate a local network over the Internet. The result? Instant on-line multiplayer without having to invite 20 of your friends to roll in every weekend. Saves on chips and beer, basicially.
Apparently the folks at XLink tested Halo 2 and Perfect Dark Zero, two XBox games, and both run on the 360 perfectly. This means that you won't have to pony up the $8 a month for XBox Live. Luckily, MS isn't as crazy as Sony about shutting out deviants and perverts who dare attempt the sin of Fair Use, but keep your eye open for a security patch.