Well, I went ahead and did a release of pacnanny. Actually I did two before I had a chance to write this post, hence the current version is 1.0.1. Since the general announcement yesterday, I squashed a couple of bugs, added reprinting of scriptlet messages, and I made all features completely optional. That last point means you can customize just how much of a pest pacnanny is.
Anyway, since this is only of interest to users of Arch Linux and friends, it suffices for me to say that pacnanny is available in the AUR. Enjoy!