Oh, we're not? I guess I'll go change it.. though, I don't know why we aren't. Nobody here seems the type (to me) that would abuse the rule too much if it were changed to accommodate colored text in signatures (as long as it wasn't distracting, or had too many colors, like this! Size changed just for emphasis..
WDIT: Sig changed!.. based on a post I'm about to make in the Mario species thread..