Apple explains in the upcoming OS X Mountain Lion will be even more emphasis on the Cocoa framework. So will the Carbon api as deprecated to be considered and for the X11-framework is now an optional open-source package is needed.
In OS X 10.8 Mountain Lion, which this summer is available and currently as a developer preview is available, it is also the deprecated Carbon api permanently depreciated. As mist Carbon support for 64bit-applications.
With the step-by-step ‘disposal’ of Carbon in the latest OS X releases and the giving of X11 and Java support to external open source projects, Apple will send more and more OS X developers in the direction of the Cocoa framework. Apple provides Cocoa for some time in OS X and iOS platform, and the company considers its native api is now sufficiently mature as the standard framework for OS X software.