Rob Scoble is reporting Google-Reader subscriber counts for popular sites. These are interesting numbers and (I suspect) a reasonably useful metric of relative popularity. But some of the evidence is puzzling.
[Update, the next day: Google provides some explanations and updated their numbers; their spider and the Google Reader page now show the same subscriber count: 4,404.]
Google Reader reports that I have 3,690 subscribers (Bloglines reports another 4,462). What’s weird is that “Feedfetcher”, their feed-crawling robot, also reports subscribers an a way that shows up in my webserver logfiles. To be precise, it reports 4,403 subscribers to my Atom feed and 1,455 to the RSS version (which is now a permanent redirect to the Atom; silly, silly Feedfetcher). Combining 1,455 and 4,462 and getting 3,690 seems reasonable, actually, assuming Google’s correcting for people who subscribe to both, and people who are inactive; it’d be kind of nice to know what’s up though. Bloglines’ robot, on the other hand, reports the same number of subscribers that the site does.