Lion specific features

I am developping a Mac application requiring Mac OS 10.6. However I am interested to add a Lion specific feature (fullscreen support). What is the way to properly manage that (I am planning to use the Mac App Store):

• 2开发者_StackOverflow different versions?
• a "special" version combining 2 version and using automatically the right one depending of the system?

Thanks

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Set Base SDK to Lion, but the Deployment Target to the oldest version you want to support, and the newer features are available via weak linking