Apple has released the Darwin source code behind its Leopard operating system to developers.

Darwin 9.0 forms the backbone of the UNIX-based operating system and is being made available to developers in the open source community, as it has been since Mac OS X 10, the first version of the OS.

Darwin 9.0 is a fully-conformant UNIX operating system that's built on Mach 3.0 and FreeBSD 5.

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