They have gathered a few sponsors, and will be giving away some prizes. PCPer has donated a XFX NVIDIA based motherboard for the event, and the group has also picked up other sponsors such as Mushkin.
Left 4 Dead seems to be the reigning game for LAN parties, with a helping of Counter Strike: Source, and perhaps some TF2 to cleanse the palate. Try to resist logging into World of Warcraft, as it is considered tacky at most LAN parties.

Personally I will probably be attending, and hopefully not make a total fool out of myself while playing these games. Hell, might even put on an impromptu discussion about current and future graphics architectures and where it looks like we will be going. There are 150 seats in total, and at an impromptu LAN last month they had 75 folks show up. So, get there early and claim your spot!