Teateam a russian speaking Mac OS developer binary patched the latest Mac OS X 10.6.2 Mach Kernel to eventually reenable support for Intel Atom CPUs. His kernel seems to be running well in 32bit and in 64bit mode. Atom CPUs are now reported as Intel Core Solo or Core Duo.
The patch seems only to consist of modifying a couple of (simply) assembler instructions to permanently set the CPU type. In the meantime Apple has released kernel sources and people are working on adding Atom CPU support in a proper manner.
Congrats Teamteam. That’s what Ilfak made IDA for ;-)