@tsiberious
It's not a service pack. It rewrites large portions of leopard code. It doesn't add a lot of new features, but makes the entire OS much more streamlined, reduces the size of core apps to mere KB's, and introduces OpenCL, changes all of the core apps to 64 bit, has Grand Central Dispatch, which makes the entire OS multithreaded, and allows multithreaded apps to be written extremely easily for the OS