As consumers closed their wallets, Uncle Sam opened his with one of the biggest spending programs in history, roughly $1.5 trillion in less than a year. Some $700 billion went to shore up shaky banks; another $787 billion paid for tax cuts and a surge in spending on new roads, green technology and a host of other projects designed to pump dollars into a shrinking economy. A separate alphabet soup of money transfers from the Federal Reserve added another $1 trillion, much of it to guarantee loans and buy up bad investments from banks that couldn’t sell them, freeing up cash for them to lend. The strategy seems to have worked, and much of the planned direct government spending is still in the pipeline. The hope is all that federal spending gets the gears of the economy turning again with enough momentum that as the federal spending spigot starts to slow down, other sectors of the economy will take up the slack. But that plan comes with potential pitfalls. At some point, the Federal Reser...