How safe is your Money Market Fund?

Vanguard released a new statement ''A word on Vanguard money market funds'' Yesterday after concerns that some money market funds were 'breaking the buck'. A BusniessWeek article ''Money-market fund's troubles spur industry moves'' has more information. Its interesting that some funds are going to report their holdings in their funds each day to reduce investor fears. An example below

Holdings of Vanguard Prime Money Market Fund (as of 8/31/2008)
U.S. Treasury: 36%
U.S. Agency: 17%
Certificates of deposit: 32%
High-quality commercial paper: 14%
Repurchase agreements: 1%