If you could have a screening process that was on par with, say, Google's, and became notorious for such a thing, I think you'd be in a position of extraordinary value. You'd be offering Google Quality Engineers who are actively seeking jobs. I think that's huge! You'd attract business that are willing to pay for the best, and you'd attract talent that wants the best pay.
The main goal here is to establish yourself as having a rigorous and "industry best" screening process. You only attract and accept awesome developers. You do all of the work in the technical screening, and you front your reputation on that. You only deal directly with candidates, and on the other end, with people in the position to hire.
Of course, there is a chicken and egg problem here. So you'd need a lot of publicity out the gate, a decent pool of acceptable candidates, or a decent set of job availabilities.
I'm tired of being asked if I know what a join is, the pros/cons of indexing, the difference between by reference and by value, various OO questions (What's an abstract class do?), design patterns, what memcached does, etc. And I'm sure places are tired of candidates that don't know these things. Solve both of our problems.