From their Mailing List:
Today is a day that we at LGP have worked towards for over two years. We are very excited to announce the launch of LGP's new site, PenguinPlay, a Multiplayer matchmaker for Linux.
Linux gamers can use PenguinPlay to find other gamers to play against, post about games on the PenguinPlay forums, and keep track of just how good they are on our highscore tables.

Coinciding with this launch, we are releasing patches for Knights and Merchants and Ballistics, to incorporate the new PenguinPlay library into these games. Patched for other LGP games are forthcoming, and our new titles, Jets'n'Guns and Sacred will be released with PenguinPlay support. For full details, see our Press Release
The Website: http://www.penguinplay.com/

Looks promising and because of this I will probably end up buying Jets'n'Guns.