Alas, this post is not about announcing such an awesomeness. But i would like to draw attention to the new, open-to-other-modules subscriptions 5.x-2.x branch and what a fantastic piece would be a small module that ties views and subscriptions together. According to Earl Miles, the creator of views:

you could grab the view, add a nid filter to the view (or argument), run the view and get the result. If there's a match, it's in the view.

. If you are up to code this module, contact me and I will help with the subscriptions parts, the API is not yet documented because it's a bit in a flux.