The invitation for an Apple Event taking place one week from today strongly suggests that the primary topic of the day will be the next major version of Mac OS X, 10.7, and that the cat-name for this version will be "Lion". Cheetah, Puma, Jaguar (the first to be marketed as such), Panther, Tiger, Leopard, Snow Leopard, and now Lion.
Recent versions have brought, in no particular order, the Kernel Extension APIs, the Acceleration Framework, Spotlight, Core Animation, Core Data, OpenCL, Grand Central Dispatch, and Objective-C 2. What might 10.7 have in store to match these?
Something, no doubt. ;-)