Apple does a fantastic job -- better than anyone -- at providing development kits that make developers' work look beautiful. They model the best experiences in the apps they ship, and provide tools that allow any motivated developer to make similarly beautiful experiences for their own apps.
It is hard for non-developers to realize how awful almost all the tools are for making client applications, particularly cross-platform ones. That's one big reason why the web has only grown and "rich internet applications" didn't take off 10 years ago. All the native options are so ugly and horrible, you might as well just use the web, which is both wonderful and an ugly kludge. The web's main benefit, in this context, is simplicity.
It is hard for developers to recognize how awful everything is because they're used to it and most have grown up with it.
Mac OS X (and Next...) has always been somewhat of an exception to this, but stuck in a niche. The iPhone has gotten developer juices flowing and now people seem primed to exploit the expanded possibilities of the iPad. But the difference is in the potential aesthetic quality of the end product.