The Mac OS X 10.6.8 Supplemental Update is recommended for all users running Mac OS X Snow Leopard 10.6.8 and resolves issues with:
Transferring personal data, settings, and compatible applications from a Mac running Mac OS X Snow Leopard to a new Mac running Mac OS X Lion
Certain network printers that pause print jobs immediately and fail to complete
System audio that stops working when using HDMI or optical audio out
For detailed information on this update, please visit this website: About the Mac OS X v10.6.8 Update.