I feel that the market right now for Django is still too small for something like this to really work. Even the open Django job boards like http://www.djangogigs.com are pretty barren. How are you going to convince employers to fork over money without proof that there are lots of talented Django developers behind the walls of your site? And how are you going to convince developers to go through the trouble of opening up their code and submitting to tests without proof that it might get them access to lots of top-notch employers?