Good idea. I'm not sure if the github bug tracker supports extension attributes, but it'd be a great place to add it. Also, people can let know that they're already working on a feature using a comment, to prevent double work.

The biggest problem will be organizational, in getting the BTC together for bounties; only a high profile member such as Gavin will have enough trust to ask for support. Or maybe there's something left in the faucet? :-)

Unrelated: what also might help is publishing a roadmap. Plan a few "bug fix only" releases before scheduling addition of new features. It's also helpful for people that wonder that direction the project is going in...

JS