With Treasury and the Fed trying every trick in the book now, the lack of cash is not a problem. If we can "print" $700 billion to buy up these toxic debts, as Dan mentioned, the gov't will provide the FDIC with as much cash as is necessary to prevent a full-scale bank run. In the best case, just the fact that people know that the gov't will guarantee everyone's bank deposits may be enough to keep everyone from trying to get their money, and in that case, Uncle Sam won't have to actually pony up all that extra cash.