Jeff Hummel wrote a nice article for Reason. Most of it isn't new and is similar to his chapter from Boom and Bust Banking.
His basic argument is that Bernanke used quantitative easing to bail out the banking system to maintain the flow of credit. This policy involved directing credit to where the Fed felt it was most needed.
This is in contrast with a more traditional monetarist approach, which Market Monetarists have emphasized. The reason to expand the quantity of money is to prevent (or reverse) decreases in spending on output.
Hummel's emphasizes some policies (much criticized by Market Monetarists) that appear counter-productive if the goal of quantitative easing was to prevent (or reverse) decreases in spending on output. First, the Fed undertook open market sales of Treasury bills to at least partly offset the expansion of loans to banks. And then the Fed introduced interest on reserves--a clearly contractionary policy.
What Hummel doesn't mention and a concern that many Market Monetarists have emphasized over the last five years, is the temporary nature of the quantitative easing. A temporary increase in the monetary base should have little effect on spending on output. However, it should be able to support particular credit markets.
For example, suppose a central bank is committed to an inflation target. Investors refuse to buy new issues of mortgage backed securities and sell off existing holdings. The central bank buys the mortgage backed securities, but insists that this is only temporary. If inflation starts to rise, it will sell off some sort of assets or perhaps raise interest on reserves. Any expansion in base money or broader measures of the quantity of money is temporary. For the most part, the demand to hold this additional money expands to meet the supply. There is little or no inflationary effect.
Perhaps more troubling, this logic appears to apply even more strongly to a central bank with a nominal GDP level target. Suppose that nominal GDP is on target. Further suppose that the central bank decides to support the President's plan for poor people to have homes, and so begins to buy mortgage backed securities. The quantity of money expands, but people hold the additional money balances--they believe that the expansion is temporary. There is little or no impact on total spending on output. This certainly appears to create an opportunity for malinvestment.