What you're mentioning is part of what I'm currently doing with a simple game prototype - its not as simple as asteroids, its more of a top-down 2D shooter, so using some astar pathing routine is involved for the client to be smart when moving around.
But the game does support solo and/or team play with each client running a socket connection against a central game server. So messages can be broadcast between teammates(I've spotted a target at x/y, etc) and clients can further coordinate macro-level strategy on their end.
Still working out some kinks with the game server and sample client, but its available to test out to anyone interested and will develop for others as interested.
http://code.google.com/p/sqlitebot/wiki/phibianviewtopic.php?f=21&t=2248Thanks
Jeremy