The following review of Mac OS X 10.6, which also goes by the name Snow Leopard, can be found here: http://arstechnica.com/apple/reviews/2009/08/mac-os-x-10-6.ars.

It really is a nice review talking about topics such as the LLVM/Clang transition, the introduction of Blocks in C-style languages, Grand Central Dispatch (GCD) and OpenCL. Read it!