Don't Call the Whole Thing Off

"The first example of policy in a liquidity trap comes from the 1930s. The U.S. economy grew rapidly from 1933 to 1937, helped along by New Deal policies. America, however, remained well short of full employment.
"Yet policy makers stopped worrying about depression and started worrying about inflation. The Federal Reserve tightened monetary policy, while F.D.R. tried to balance the federal budget. Sure enough, the economy slumped again, and full recovery had to wait for World War II."

Paul Krugman in The New York Times warns against declaring victory over the recession too early.