There are some interesting tid-bits of information about under the hood improvements scheduled for Mountain Lion in the official press release:
Hundreds of new APIs give developers access to new core technologies and enhanced features within OS X. The Game Kit APIs tap into the same services as Game Center on iOS, making it possible to create multiplayer games that work across Mac, iPhone, iPad and iPod touch. A new graphics infrastructure underpins OpenGL and OpenCL and implements GLKit, first introduced in iOS 5, to make it easier to create OpenGL apps. Using Core Animation in Cocoa apps is easier than ever, and new video APIs deliver modern 64-bit replacements for low-level QuickTime APIs. Enhanced Multi-Touch™ APIs give developers double-tap zoom support and access to the system-wide lookup gesture. Kernel ASLR improves security through enhanced mitigation against buffer overflow attacks.
It’s interesting to see Apple throw its weight behind Games development on the mac, an area it is often criticised for not properly supporting.