I actually built something similar for my rss feeds and some bookmarks using the python "Clips" library but i felt that it needed to be a feature in a broader product, so i decided against trying to build a business with it. The difference with mine is that the algo automatically summarized the content for you.
That's one way to approach this problem, and there are a couple companies trying it, most notably Summly. We believe that software-made summaries are not good enough, which is why we down the human-written summaries road!
