Apple introduced the GLKit framework for iOS 5 a year or so ago. GLKit greatly simplifies programming with OpenGL ES and smooths over some of the differences between OpenGL ES versions making it easier to adopt the latest and greatest graphics technologies.
Mac OS X 10.8, Mountain Lion, brings most of GLKit to the desktop. That's great for the same reasons the framework is great for handhelds. It also makes porting from iOS to the desktop easier.
To get started with GLKit on the desktop, I ported the example program in my InformIT article, Adding Open Source 3D Physics to Your iOS Applications, from iOS to Mac OS X. While porting, I converted the example to a multi-document application with all the bells and whistles. Most of that sort of thing comes with no effort thanks to Xcode.
The InformIT article explains how the example works and how to integrate the Open Source Bullet Physics library with Cocoa/Cocoa Touch applications.
Note: The Mac OS X version of the example uses a custom PTEffect class instead of the GLKBaseEffect class that comes with GLKit. I was unable to get the GLKBaseEffect for Mac OS X to implement diffuse lighting or proper transformation matrix behavior. I'm still investigating, and if it isn't something I've done wrong, I'll submit bug reports to Apple. For right now, as far as I can tell, GLKBaseEffect for Mac OS X is broken or not fully implemented.