Today Apple released Mac OS X 10.6.5 which removed the AirPrint capabilities that were present in previous versions of the OS.
Steven Troughton-Smith has detailed how to return the AirPrint functionality to OS X 10.6.5.
You need the following files from a prerelease version of 10.6.5: ● /usr/libexec/cups/filter/urftopdf ● /usr/share/cups/mime/apple.convs ● /usr/share/cups/mime/apple.types
The final key thing is you have to remove and re-add your printer in the Print & Fax preferences pane. Once you do that (and share your printer in the Sharing preferences pane) it should show up on any iOS devices that support AirPrint.