I have my emergency money currently in a money market fund, but I recently moved to CA. I was curious about what factors should be considered or should I be looking into if I want to move my emergency fund to a tax-free money market fund?

Well, besides the obvious one of whether your tax bracket makes a tax-free money market preferable, I'd look for investment policy. What grade securities do they invest in? I'd make sure it was B or higher. How easy it is to get the funds? Vanguard has a check writing option for checks of a minimum of $250. Also, I'd like it to be tied to my regular checking account so I could ACH transfer between accounts. (With ACH transfers you get free two to three day electronic transfers.)