Time and Excel

No, this isn't about how much time I spend with that particular spreadsheet app, though that's probably worth a post at some time. It's about a little bug I discovered on Friday in the way Excel compares times with one another. It's odd, hard to stumble upon, and not easily summarized. So while I try to figure out how to report such a thing (yes, really), I've attached a pdf of a demo spreadsheet that reproduces the problem.
For the curious among you.