An OO language without some sort of an OO library is not that much to get excited about today. I'm a big fan of Objective-C if you can't use something like Smalltalk. It maintains the same principles of simplicity and uniformity that Smalltalk does. But there's no "standard" (defacto or not) library for it. Well, there is. It's called GNUstep which is basically an open source version of the NeXT class libraries. And they try to keep it relatively compatible with the things Apple adds to their Objective-C libraries.
The problem with GNUstep is that it assumes you want to use it in the context of the GNUstep desktop environment. It wants you to have a certain directory structure, and certain environment variables. But when you just want an NSMutableArray (OrderedCollection for Smalltalkers) for some command line tool, you don't want all of that stuff.
Luckily, someone's stepped up to the plate to fix that. Andrew Ruder has built an alternate version of the GNUstep base libraries that doesn't require anything outside of itself. Don't have to use GNUmakefile. Set environment variables. Or source some script into your login .bashrc. Andy very helpful helping me get it built and usable. The project is called Sidestep. You can use svn to download it, compile it, and then compile Objective-C apps against it. My hat's off to the guys that took the effort to make this happen.
Sadly, the GC stuff still doesn't work. But you can't win all the battles in one day.