Licensed Computer Geek
I was looking through my Library/Preferences directory, cleaning out orphaned prefs, and I saw an interesting file. It's called "Updatable Items," and has a Software Update icon. Perhaps other applications can make use of Software Update's features, and not just OS X, IE, etc. The file is kind of old, so I hope it isn't a leftover from the Public Beta days. You can take a look below; the screenshot is only about 60 KB.