I decided to release my old set of flavour templates on the flavour registry and in so doing totally foobarred all the times on all the files of my blog. I recovered most of them (because I have a mirror that's usually off by a few days), but then I had to guess on the times for the latest four entries.
So that sucked. Given what I just went through, I'm beginning to think it's a terrible idea to use the timestamp on the file as the mtime. Blech.