Well, I've written a modification called Thread Title Coloring (Search if you're interested) that does that, but it's on a global scale, allowing the coloring of different types of threads: Closed, Stickied, Moderated, etc.
If you've got any experience with PHP IF Conditions, then it wouldn't be difficult to modify it to act in such a way... in fact, you've just given me an idea for a new version.