Crappy Windows interoperability with the rest of the world
Recently, I've had the need to distribute things to customers in .zip files. I create these .zip files on my Mac, using the Finder, which is a perfectly acceptable method for doing so.
If I send the resulting .zip file to another Mac user, a Linux user, or a Windows XP user, they can all unzip the file without issue. I'm also told that users of third-party utilities don't have issues, either. However, if I send this same file to a Vista user (and presumably a Windows 7 user), they have problems, and I have to create the .zip file via another method. This is completely annoying, and doesn't make any sense to me. Not from a "Oh, they did something different that broke compatibility" standpoint, but more from the "Did they actually test interoperability at all?" perspective.
The less the Windows guys support interoperability with standards, the less relevant they become.
And, that is my short rant of the day...