It's the standard language where I work. The object model is much more rigorous* and lighter (you can see the SmallTalk in it) than C++; it feels like a minimalist OO C, which of course is what it is.
* By which I think I mean easier to express formally and far harder to play clever games with, which is what I always do with C++, mainly just because I can :p
No. In terms of desktop OS, we target Win and *nix (generally with the same source but compiled separately on each platform). We have never targeted any Apple OS.