Tyler Cowen sums up policy lessons from the financial crisis so far (emphasis mine):
First, don’t assume that the first wave of a financial crisis is the final act. Circa 1931, many people thought that the global economy was recovering, until an additional wave of financial crises caught fire in Europe and later damaged the United States. Mr. Bernanke is a scholar of exactly this period.
Second, no matter what laws are written, good central banking is the most powerful and most influential financial regulator, if only through the broad management of liquidity and safety. The euro zone has put too much responsibility on national governments and too little on its central bank.
Third, good regulation should take account of our rather extreme ignorance. That means emphasizing the more general protections, as embodied in a ready supply of safe liquid assets, rather than obsessing over the regulatory micromanagement of particular bank activities.