On the technical side I found the modelling of getters and setters as pull and push collections (IE/IO) interesting. In a previous C9 video I believe Erik mentioned his affinity for "first-class" constructs. Mapping getters and setters into these interfaces make them more first-class in a way. So for example one could subscribe to an accessor and listen to "settings" (or "gettings" too, actually). I love that generality.
How about giving incentives like 100% profits and free tools for the first one or two apps instead?
That said, Microsoft used to create reference applications like Family.Show to show how to build good applications for their platform - or rather they wold pay another company to do it. Is that still the case? (And how about upgrading those apps for familiarity for devs?)
Maybe if you want to attract dev's you need to set more high quality examples and release the source on GitHub and Codeplex. Also comparative code for other platforms to show off benefits of async etc.