Here is what the apple site says:
With Snow Leopard, Mac OS X makes it easy to use scripting languages as full application development tools. Snow Leopard ships with support for the RubyCocoa Bridge and the PyObjC bridge. These two bridges give developers access not only to system APIs, but to Cocoa frameworks such as AppKit and Core Data, enabling you to build fully native Mac OS X applications in Ruby or Python. The RubyCocoa and PyObjC bridges allow you to freely mix code written in Objective-C with code written in the scripting language. You can quickly build prototypes and then optimise by implementing performance-critical pieces in Objective-C.
How could Python help in this case?