[kej]

I feel like the job board (yours, Monster, Dice, whoever) is in a unique position to solve this problem. You can ask each side for their salary range but then don't disclose it to the opposite side. You can then match candidates to compatible jobs and everyone knows up front that the desired ranges overlap.

[Spoom]

This is a really interesting idea. I would expand it further... OkCupid for employment. Outsource algorithmic and language knowledge measurement to something like TopCoder and add that as a potential dimension on which to match. Education, clearances, experience: these could all be match dimensions.