Sources internal to Apple have informed 9to5Mac that OS X 10.6.5 has been finalized and circulated within the company. 9to5Mac also notes that such pre-release updates "usually come in one to a few days prior to public launch."
10.6.5 is required for most AirPrint functionality in iOS 4.2. Since iOS 4.2 just reached GM status, it's likely a public release for OS X 10.6.5 will roughly coincide with the public release of iOS 4.2. Both OS releases are expected within the next week or so. We'll let you know a