Though it's not noted in the transcripts of the event, John Kerry (my father's favorite candidate) also said that he uses a mac.
Cool :)
... meanwhile Bush uses a Dell (see the interview where he says: "I guess I'm not supposed to be talking about brands, but since Michael Dell is my good friend and Dell is a Texas company, I'm the owner of a Dell computer.")
So this picture must have been staged.
I bet he often asks "Now where is the *any* key...?"