bonch writes "Apple has open sourced libdispatch, also known as Grand Central Dispatch, which is technology in Snow Leopard that makes it easier for developers to take advantage of multi-core parallelism. Kernel support is not required, but performance optimizations Apple made for supporting GCD are visible in xnu. Block support in C is required and is currently available in LLVM (note that Apple has submitted their implementation of C blocks for standardization)." Update: 09/11 15:32 GMT by KD : Drew McCormack has a post up speculating on what Apple's move means to Linux and other communities (but probably not Microsoft): "...this is also very interesting for scientific developers. It may be possible to parallelize code in the not too distant future using Grand Central Dispatch, and run that code not only on Macs, but also on clusters and supercomputers."