I was glancing at my server logfiles, and was impressed, as always, by the huge number of feed-readers out there. So I made a graph of how often the ongoing feeds have been fetched so far this year, and the popularity of RSS vs. Atom 1.0.
Note that the Y-axis bottoms out at 200K, so the graph overemphasizes the growth relative to the total traffic. Bottom line: During prime-time hours, the feeds are getting fetched multiple times per second.