Apple has seeded a new version of the upcoming Mac OS X 10.6.5 release. The last Mac OS X 10.6.5 build was released two weeks prior. According to MacRumors the new build affects 3D graphics, iCal, Mail, QuickTime, Time Machine and USB Devices.
It is still completely unclear when Apple will release OS X 10.6.5 to the public. The last major update for Mac computers happend in June.