Like others have said, sometime around the end of next year.
Man, next year's release list is looking killer. We have truly entered into the golden age of gaming. In 2007, we had amazing release like Super Mario Galaxy, Uncharted, Metroid Prime 3, Halo 3, etc. This year, we've seen MGS4, SSBB, MKWii, GTAIV, DMC4, and will be soon getting LBP, Resistance 2, Gears 2, Fable II, etc.
Next year, God of War III, Uncharted 2, Killzone 2, White Knight Chronicles, Star Ocean 4 and others are all but confirmed, and it's extremely likely we'll see Zelda Wii and Team ICO's next game before the end of the year in addition to all of that. Maybe Kid Icarus will surface as well?