Here's an interesting fact about Microsoft Points—the fake currency used in the Xbox 360 and Zune Marketplaces—that we just learned yesterday: points expire. If you've got promotional, contest, or giveaway points from Microsoft for doing something or other, you should check out their billing site. These actually expire after a given time. The good news is that points you buy normally don't expire, and would be completely ridiculous otherwise. Just keep an eye on your stuff.