One word: wow. This is really very awesome indeed. Follow a site even when it doesn't have a feed. There are other ways to do this but Google's basically just provided the easiest way of all. Very, very useful indeed! POST-EDIT: this doesn't actually produce an RSS feed. It's just a Google Reader thing, doesn't integrate with anything else that I can see. You can't even put it in a folder in Google Reader then make that folder public and get a feed off that. Still, it's better than a poke in the eye with a sharp stick, as they say.
It still seems so hit-and-miss – some things 'go viral', others do not. Was seeding involved here? Has it just become popular because it's good?