I make the case over at the National Review that conservatives should support QE2. The punchline is that tight monetary policy almost always leads to more government spending and intervention. The best examples of this are the early 1930s and late 2000s. In both cases effectively tight monetary policy turned what could have been ordinary recessions into great ones. These great recessions, in turn, opened the door for more government involvement in the economy. From this perspective, QE2 is nothing more than a long overdue attempt by the Fed to set monetary policy right and thereby reduce the likelihood of further government intervention in the economy.
For another perspective on why conservatives should support QE2 see Scott Sumner's Open Letter to Conservatives.