I stepped away for a cup of coffee, and when I came back, there's a new version of Firefox.
I thought my co-worker was kidding, but sure enough, when I started Firefox, it started downloading the installer for version 7.0. Out of curiosity, I went to the options panel to look at the update history. It showed Firefox 5, then Firefox 6, both listed as "security updates" — version 6 installed only last month.
Curiously, after installing version 7, the "update history" list was cleared out. A little embarassing, perhaps?
Seriously, Firefox; this is just silly.
Besides, Chrome has you beat by miles (version 14 as of this post).