During the panic in the fall of 2008 some interpreted the explosion of the Fed's balance sheet and the monetary base (MB)—currency plus reserves of banks at the Fed—as an appropriate monetary policy response to a shift in the demand for the monetary base. That monetary policy should try to accomodate such shifts in demand is a classic monetary principle.
Evidence offered in support of that interpretation was the sharp drop in the money multiplier (m)—the ratio of money (M) to the monetary base (m = M/MB). The claim was that the Fed offset the decline in the multiplier (m) by increasing MB, thus leaving the money supply (M = m times MB) comparatively unaffected by the drop in m. Indeed there is a striking negative correlation between the multiplier and the monetary base during the late 2008 and 2009 period, as shown in this graph.
However, I argued in a Business Economics article at the time that this striking correlation had another interpretation. It was due to a reverse causation: the increase in the monetary base caused the multiplier to decline as banks simply absorbed the inflow of reserves. The cause of the increase in the monetary base was the need for the Fed to finance its loans to bailout financial institutions, provide swaps to foreign central banks, and eventually make purchases of mortgage backed securities in its quantitative easing program—a strategy I called mondustrial policy in part to drive home this reverse causation.
But the very severity of the panic in 2008 makes it difficult to convince people that there was not a panic-driven increase in the demand for the monetary base at that time, and I frequently hear economists and economic students sticking to the original interpretation. In this respect QE2 provides more convincing evidence for the second interpretation. The months since the start of QE2 are not even close to the panic observed in the fall of 2008. So it is much more difficult to argue that the Fed was responding to a panic-driven or otherwise autonomous increase in the demand for the monetary base. Much more likely is that—as in the fall of 2008—banks simply absorbed the increased supply of the monetary base which the Fed used to finance QE2. In fact, if you look at the chart (which goes through April 2011), you can see the same inverse relationship between the money multiplier and the monetary base during QE2 as during 2008--2009
Regarding mondustrial policy, several new articles written this Spring expore its implications from an Hayekian perspective, raising concerns similar to the ones I mentioned when I coined the term, but with more emphasis on accountability, rules, and discretion.