That's an excellent question. It's been debated, of course, in the States as part of their examination of reregulation. Currently the U.S. is the only system where the central bank regulates the banks--inspects, audits, regulates the banks. The other major countries in the world do not. They've divorced it from the central banking system.
There are arguments for and against. The argument is that the central bank has a deeper understanding of the macroeconomy and monetary policy and monetary conditions than anybody else. The counter-argument is that they are in a conflict of interest in terms of their mission, somewhat similar to CMHC; they have a conflict between their commitment to social housing, which is very legitimate, and their commitment to being a mortgage insurance company.
The central bank, if it becomes the regulator of banks, is in a conflict because its primary job is to ensure stability of the financial system, integrity of the currency, and moderate price inflation. And yet, if they're responsible for banks and they have to bail out a bank from time to time, they want to do things on the monetary policy side to help that particular bank.
So I'm also sitting on the fence, because I've seen very good arguments on both sides. But the preponderance of the evidence is that in the G-7, only one country at the moment has given the regulatory authority over banks to the central bank, and that's the United States.