This could be really big.

The source, who has seen both the Unix System V source code and the Linux source code and who assisted with a SCO project to bring the two kernels closer together, said that SCO "basically re-implemented the Linux kernel with functions available in the Unix kernel to build what is now known as the Linux Kernel Personality (LKP) in SCO Unix."
Read about it hear.

http://www.eweek.com/article2/0,3959,1123176,00.asp