Apple open source Grand Central
One of the highlights of the behind-the-scenes changes in Mac OS X 10.6 Snow Leopard was the addition of Grand Central Dispatch. Apple have now open sourced the code to Grand Central under an Apache 2.0 licence. Grand Central is a user and kernel space library which adds new language features, runtime libraries and other enhancements to support concurrent code execution on multi-core hardware. Grand Central doesn't solve the design issues of parallel code, that is still left to the developer, but it does make the process of spinning off threads more efficient by managing the threads execution on available processor cores.
libdispatch is the user space API to Grand Central, which has been just been put online. Other parts of Grand Central can be found in other projects; the kernel code is found in the xnu project, the blocks runtime has been incorporated into the LLVM compiler-rt project and the required language extensions into clang, the C compiler for LLVM. These components are also under an Apache licence.