That doesn't mean you should make a HN post with your entire idea diagrammed and annotated. All you need is a gist; "a social bookmarking service" or "text-message notification system" is enough to start correspondence.
Any service that will develop your product for you is not going to be worth it, period. This needs to be a collaborative effort under your wing. The developers actually working on the idea need to have their own stake in the product, moreso than a paycheck from a service that might build 1,000 dynamic websites in a year.