OS X Daily confirms widespread reports of the loss of support for Intel's Atom processors in the Mac OS X 10.6.2 update released yesterday, confirming on-again, off-again claims of the change in developer seeds of the update. Given that the final public release of 10.6.2 is labeled Build 10C540, the same as the most recent developer seed that reportedly lacked Atom support, it comes as no surprise that the public release carries the same change.
Quote - If you have an official Apple Mac then go right ahead and update to Mac OS X 10.6.2, but if you have a Hackintosh Mac Netbook... well you will want to hold off. It has been confirmed that the final release of 10.6.2 kills Intel Atom support officially. Hackintosh Guru StellaRolla reports:

"The netbook forums are now blowing up with problems of 10.6.2 instant rebooting their Atom based netbooks."
Intel's low-power Atom processors are widely used in netbook computers, a market segment in which Apple does not currently compete. Netbooks have been popular targets for users to modify into "Hackintoshes" to run Mac OS X, providing users with a low-cost Mac solution in a small form factor machine.

It is unclear why Apple has chosen to remove Atom support from OS X at this time, although speculation has centered around the possibility that the company is attempting to make it more difficult for users to build their own netbook Macs ahead of a launch of the company's much-rumored tablet device. Apple had been rumored to be looking to adopt the Atom platform for its tablet, but the company's April 2008 acquisition of low-power ARM chip design firm P.A. Semi signaled a shift toward a possible future in-house chip design for the device.

News source: Mac Rumors