This is about a year old, but very relevant here. Timothy Ferriss, author of “The 4-hour workweek”, interviewed Robert Scoble and filmed his RSS reading process (he’s suscribed to more than 600 feeds!).
In the end, perhaps unsurprisingly, the magic relies on being really quick at judging an article from its title, its overall look and other cues. There are a couple of technical tips, though, about using the Google Reader interface efficiently, like relying on keyboard shortcuts.
Here’s the video: