If he wanted to postpone it, he would have suggested a time and date, wouldn't he? Lacking that suggestion, I'd call it a cancellation disguised as a postponement to who knows when.
As far as hammering together a solution to the financial crisis, neither Obama nor McCain is required. There are 98 other senators and 435 Representatives. And their staffs. And the Fed, and its staff, and the Secretaries of Commerce and the Treasury, and THEIR staffs.
ALL Obama and McCain have to do is to vote. Anyone who can't multitask to this degree does not belong in the White House.