William White has a new working paper available through the Dallas Fed, "Ultra Easy Monetary Policy and the Law of Unintended Consequences." In the paper he argues:
The unexpected beginning of the financial and economic crisis, and its unexpected resistance to policy measures taken to date, leads to a simple conclusion. The variety of economic models used by modern academics and by policymakers give few insights as to how the economy really works. If we accept this ignorance as an undesirable reality, then it would also seem hard to deny the possibility that the policy actions taken in recent years might also have unintended consequences. Indeed, it must be noted that many pre War business cycle theorists focused their attention on precisely this possibility.