Password protection is a good issue.  Obviously its not as simple as a native web application where we can just hash the users password so never actually store it in plain text.

For Gmail users we can use XOauth, which helps, but for other services we will have to store login details somewhere.  We are currently working on a way of encrypting the passwords that are stored in case of security breaches, but its definitely not an easy task at the moment (our private alpha is just using Gmail users).

Edited: wrong response :)