I ran across a current article from the WSJ highlighting that some municipalities may need to contemplate Chapter 9 bankruptcies:
The economic slump, however, is forcing debt-laden cities, towns and smaller taxing districts throughout the U.S. to consider using Chapter 9. As their revenue declines faster than expenses, some public entities are scrambling to keep making payments on municipal bonds. And that is causing experts to worry about the safety of securities traditionally considered low risk.
Chapter 9 bankruptcy is seldom employed and generally unknown to most of the populace. It provides very specific protections (from US Courts):