Why is the USA Squad for the 2009 Gold Cup lacking so many good players?

So many of the top players from the '09 Confederations Cup will not be playing in this years' Gold Cup. Why is this? Players like Bocanegra, Onyewu, Dempsey, Donovan, Bradley, Altidore, etc won't be playing in the '09 Gold Cup. Are they just being rested for WC Qualifying? I guess the 2011 Gold Cup is much more important since it leads to the 2013 Confed Cup but still. The '09 Gold Cup Squad is basically the B Team but I'm glad Adu will be getting more experience.