I think I figured out what was making my Google rank drop. I had changed the way the archive pages are linked. I started using a pull-down menu instead of straight links. As a result, the pages weren't getting linked at Google and my ranking apparently dropped as those linked pages expired from Google's cache.

I changed it back to straight links primarily so Google can index my pages (thus making that search box on the right side of this blog ever so more useful). It's nice that I'm back to number two, but I guess this also shows how insubstantial that ranking is.

BTW, I swear this is the last time I'll talk about my Google ranking. Well, for a while at least. ;-)