There's at elast 3 peple in RGW on the beta and I guess there's more in the guild doing the same. If we have enough maybe we could make a Dead Men Testing mini guild? Or at least a chat channel.
Probably not a lot of point right now with the content already out, but in the run up to 5.0 Kung-Fu Panda then I'm pretty sure there will be enough to PTR test new raid content as quite a few have opted for the year's pass with the guaranteed beta entry. Personally I pop onto the PTR when I can during boss testing, not so keen on the levelling side of beta testing though!