If anyone else has been checking, you might have noticed the every other day upgrades on Steam's bandwidth. It's gone up about 2,000MBs in the past 2 weeks I believe, and this brings me to my theory. I think, and am hoping, that they just don't think they have the bandwidth they need to do this yet, so, if I am correct, as soon as they feel they can handle the strain on the system, they will release the Beta. The only other thing I could see pushing it back is the threat of the DDOS attacks, and if that is the case, I think it may still be a good while until we see it.