I don't know if Paladin is still working on an Instant Messenger package for use at DGA events, but in my wanderings, I've come across something that might work well. Its open source, and the server package seems to be designed primarily for *nix.
There are plenty of clients for it, or so I've found, that are set up for most major OS platforms. It even supports both private network setup and general online use, so theoretically, if someone had the server space, GU and DGA could have their own online IM community, which could then be mirrored on a DGA server at DGA events.
IM at a lan would rock... You wouldn't have to get up in order to talk to the person you need to :P
Plus, if your kinda new to the LAN scene like me... you can learn who everybody is by their IM handles... Instead of walking around looking at their CS screens and hoping they press tab :P
to play on low pings and to socialise? This way, no one would get up and say hi, they would just chat to each other like they would if they were at home on the net :P