The last topic on a beta is fairly well back and needs a bit of looking for. http://www.gamesas.com/index.php?/topic/1102578-brink-beta/ , bring it forward in the forum if you want to discuss things further.
It is worth noting that Nick Breckon posted this in that thread -
Paul Wedgwood answered this recently.
“We’re still talking about what the right thing to do is there. In terms of project status, we’re pre-beta, so we’re doing a lot of balancing, working out what works, what doesn’t, cutting things, that kind of thing.
“Probably when we get to around beta, we’ll make that decision, then Bethesda will make any announcements.”
http://www.vg247.com/2010/05/07/splash-damage-still-talking-about-possible-brink-co-op-demo/