I also found that reading Mint.com's "Privacy and Security" FAQs raised more questions than it answered.
How do they "ask for your online banking user name and passwords" but not 'see' the information (as they claim)? They must be finessing the meaning of 'see'.
Who are these "online financial service providers" where my "online banking credentials are stored"? They aren't named, but the wording suggests they are someone other than either Mint itself or my own financial institutions. If these are the most important link in the chain -- the place where my credentials are stored! -- I have a right to know who they are.