Two programmers, calling themselves Mifki/Vitaliy and Semthex, released new kernels by taking with opensource XNU tree and applying necessary patches to run the kernel on non-apple hardware. Mifki's goal was to release the kernel with as few patches as possible, that will be able to run on close-to-Apple hardware. Semthex's goal was making his kernel more compatible with legacy hardware, missing some of the crucial features.
Both kernels allowed most of the updated kexts/frameworks to work, making properly configured white-box PCs operate more like genuine Apple computers. While Mifki has only updated his kernel once, Semthex updates it regularly and has added AMD, VMWare and SSE2-support in his newest version. Semthex released his hacked kernel sourcecode on his webpage. On December 24 he also released the latest patches for the SSE3 kernel as a diff file for his original source tree as a Christmas present to the community. Special attention should be given to the SSE2 emulation which Semthex developed together with Rufus. This emulation is the first really complete emulation of all SSE3 instructions in the OSx86 history. The old SSE2 emulation were incomplete and only emulated 3 of the available SSE3 instruction and slow compared to the new emulator. This effort enabled even SSE2 OSx86 users to run e.g. iTunes 7 or high end 3d applications on their computers.