If you track your blog’s RSS subscriber figures as closely as I do, you’ll know that the number of people downloading your RSS feed tends to drop markedly at the weekend.
Yesterday mine went up though. This is probably because yesterday Google started reporting subscriber statistics when it requests your RSS feed on behalf of Google Reader subscribers.
Previously this didn’t happen, which meant that it wasn’t possible to work out how many RSS subscribers you had through Google Reader – most statistics packages just counted Google Reader as a single subscriver, even though in reality you may well have multiple people reading your feed through Google Reader.
More information is available from the Google Reader blog, Feedburner and Fedafi.