It has gotten to be kind of rediculous. :-/ Not the way the que works, but that there are this many people in the first place.
As I understand it, PBE signups have been suspended due to the huge flow of people.
What if the signups were reopened, but users who do not sign in regularly, or alternatively, who do not post feedback on the PBE forums have their accounts automatically suspended for a period of time? This might help prune out those who are just using the PBE for personal purposes, while opening it up again to more genuine testers.
The one complication I could see could be a flood of secondary account-making to bypass suspensions.
The previous suggestions of idle-kicking is even better, provided idlers actually are a significant part of the problem.