If you didn't know, cross server PVP doesnt exist in SWTOR. They want to keep the feeling of rivalry and server pride. They also discussed a system that would help fill BG queues by putting in lower level players with stats boosted to the 90% the appropriate level.
Well this article just made me very interested in the Guild system and its interaction with PVP.
You can set Guild Alliances and Adversaries. Adversaries are more likely to have their guild matched up against yours in battlegrounds.
thats pretty fuckin cool.