There is no legal way to do it. The closest you can do, is to install Darwin (opensource), and GNUstep (opensource). Then you can develop Openstep/Cocoa appli

There is no legal way to do it. The closest you can do, is to install Darwin (opensource), and GNUstep (opensource). Then you can develop Openstep/Cocoa applications on your non-Apple laptop legally and in total freedom. If you have customers who would want a MacOSX executable, you would then give them your sources, they would download Xcode, and they would compile them. This is why the GPL has been invented (or other licenses such as BSD, MIT, etc). Now of course, GNUstep doesn't track the evolution of Apple Cocoa very closely. Your application will be compilable for MacOSX if you take some care to write it portably, and you won't be able to take advantage of Cocoa specific features, only the most vanilla and plain Openstep features. Depending on the kind of application, this may be more than enough.