I'm not greatly worried about Vanguard's money market funds, but I do admit that the news gives me pause and makes me consider the amount of money I have in money market funds versus FDIC insured account.
Last year when SHTF I made sure all my emergency fund was in FDIC insured accounts. The other short term savings I hold is generally earmarked for something specific (a car, a large payoff amount for student loans etc.) and doesn't sit there very long, but good to remember these accounts are not backed by the FDIC.
Although, these days, isn't everything 100% guaranteed by the government, including the value of my baseball card collection? ;-)