A great article for developers: Exploring Leopard with DTrace. And Matt Gemmell has a fantastic rundown of all the great new Leopard features and API’s in his Get rid of your code with Leopard. I wish there were easier ways to use all of them without inexorably tying your software to 10.5, though. I’ve resorted to loading the QuickLook framework dynamically in DFX 4 so I can use it while still retaining Tiger compatibility, but that’s an easy case because there’s really only one API call I have to manually look up. Weak linking helps (thanks Apple!) but I don’t have a good structure set up for integrating a more complex framework without a lot of painful code. Anyone have any ideas out there? And no, “force your users to upgrade to Leopard” is not a viable answer in my book.