Apple's Grand Central Dispatch technology introduced in Mac OS X 10.6
"Snow Leopard" was open-sourced under the Apache license last month by Apple and now it has worked its way into FreeBSD. This software, which helps in optimizing applications for multi-core systems, has ported the libdispatch library from GCD to FreeBSD and made Grand Central Dispatch more POSIX friendly.
Additionally, a Clang compiler package that is blocks-aware is also available, which can run well in a GCD environment. A FreeBSD Port of Grand Central Dispatch / libdispatch is now available, while the changes involved will be merged into FreeBSD 8.1 to allow the GCD library to work "out of the box" on this BSD operating system. It's currently being explored whether parts of the FreeBSD base could benefit from using libdispatch.
This information regarding FreeBSD and Grand Central Dispatch can be found in the FreeBSD Quarterly Status Report