So, various folks are in the process of porting Grand Central Dispatch to FreeBSD (c.f. http://libdispatch.macosforge.org and http://lists.macosforge.org/pipermail/libdispatch-dev for mailing list discussion on the topic) and are making good progress, but one of the issues they're running into is support for Blocks in FreeBSD.
On the one hand, they could try and back-port the gcc changes from http://www.opensource.apple.com/source/gcc/gcc-5646 and solve the problem that way or, on the other hand, they could just continue FreeBSD's inexorable march towards Clang and get the blocks support as part of compiler-rt. The only problem seems to be that the build support for Blocks in compiler-rt isn't wired up yet, which came as something of a surprise to all involved given that people have been talking about Clang and Blocks since this summer.
Is there a roadmap for this anywhere that we can read? If this simply has not been done due to a lack of resources, the GCD porting folks could perhaps help move this along, assuming they had appropriate access to the bits.