Actually, on thinking about it a bit more, it has a lot of similarities to a whole bunch of coordination problems that I worked on many years ago in the mobile phone industry. There was a problem was coordinating resource usage between a set of mobile phone base stations.

In the OP, you talked about a payoff curve for an individual server taking on a job based on its current loading. This is effectively a metric for the desirability of that server taking on another job, and that in turn would allow the supervisor to auction off jobs, assigning each job to the server which will benefit most from taking it.

You could even go one step further and implement a genetic algorithm classifier system. Each server would have a rule set for bidding for jobs coded it into the GA genotype. Every once in awhile a lower priority coordination process runs a generation of the GA, replacing the rule set on some of the less efficiently running servers with the offspring of the other more efficiently running servers. In this way the population of surfers evolves towards rulesets for bidding for jobs the drive the efficient use of your server resources.