For the last couple of months (since September 08, apparently), the calendar links haven't been working well. They were actually pointing to the comments, rather than the articles. This happened due to Blogger.com changing their post feeds (you can read more here and if you've been using this particular calendar widget, find a fix here).
I didn't even notice the problem, until a diligent reader notified me. Thanks Shlomo!
Rest assured, the head of my QA department has been sacked for this. The position is now open