
I have managed to build Apple's development toolchain (a self-host, however the "Darwin SDK" has also been ported to Linux). I usually don't like to mention people's personal pages however, the blog server with all the info appears to be a little unreliable, so see the info box on ameaijou's Twitter page. There is also a sequel to Amit Singh's Mac OS X Internals coming soon. She has been the most active developer that I know of in this area. Furthermore, thanks to a (now Apple-employed) developer who goes by the handle winocm, we have an ARM port of the xnu kernel. There are also success stories booting OS X Yosemite within QEMU. However, the Hackintosh community is still highly active, meaning that one of the few open source non-Apple bootloaders capable of booting xnu (Chameleon and forks) is still maintained and can boot Yosemite. After two years there still appears to be very little interest in this sphere.
