I was just contact on Twitter and email by a Developer who has iOS 4.2 GM and 10.6.5 working via AirPrint on is Touch and iPad. He was originally using the Mac OS X 10.6.5 beta versions and updated to the release version today, after doing so printing still working with his iOS devices, he then applied the combo updater to his Mac and the printing still works for him. Printing is being done via an older HP 1300. This is all done running iTunes 10.1 beta 2 for developers, but adding that to my machine changed nothing.
Take a look at the screen shots that he sent in below.
[Updated: 11/10/10 at 8:33 PM] Looks like this is a result of a preference pane that is not overwritten in the released version of 10.6.5 – so if you have the dev betas installed this will probably work for you.