cunicula can write some code that implements proof-of-stake and then tie it into bitcoin/bitcoind using -blocknotify.
Haha. I'm an academic economist. I can't code anything beyond 'Matlab code'. Thus, I hope you can understand why I must be all talk and no do.
Someone else has to take my idea and run with it, or it will never happen.
Of course, I'm happy to help in anyway I can, but my help is intrinsically limited.
If you're looking for something that is basically bitcoin compatible and someone who can make it happen, Meni might be the appropriate person to encourage.
My idea is fundamentally incompatible with the current bitcoin reward system. It has to exist as either a hard fork or an altchain.