Apple are set to release their next OS X update Snow Leopard on 28 August 2009. There are many refinements including native Gamma 2.2 like Windows, soft proofing in Preview, faster back up to Time Machine, and full 64 bit support.
Be sure to check your apps support OS X 10.6 before unleashing Snow Leopard! Microsoft Expression Media 2 has an issue rendering some Raw file formats like Nikon NEF. Use “Apple” as the “Preferred Engine” if it affects you.