At the risk of getting even more off topic, Objective-C is one of gcc's dialects and works on Linux and *BSD just as fine as on Mac OS X.
Yes, I know, and so is C++. Nevertheless, neither is allowed in Wine's source. I can argue rationale if you like, e.g. we don't want to restrict ourselves to gcc, but my opinion doesn't mean much, as it's Alexandre's decision. --Juan