Safe enough for your money: Mint.com and other personal finance sites keep it real
First off, it is important to note that you don't make any transactions from inside Mint, which affords solace to some wary users. The most impressive piece of information about Mint.com's security is that the back end that runs Mint, called Yodlee, is also used by many of the top banks in the industry. All of these precautions should combine to give most users the same sense of security when using Mint.com to manage their personal finances as they have with their own bank.
Even though I am part of the younger generation which seems at time to jump on new technology, I have been hesitant to start using any of these third party online budgeting systems mainly due to security. Thankfully, it appears that my fears were unfounded and Mint.com appears to be using good policies and software to safeguard users' information and money. Stay tuned, in the near future I'll be looking into the security behind a Mint.com competitor, Wesabe.