We have extended the support for automatic account synchronization via offline data storage to Firefox 3 users. Firefox 3 users can store their authentication information locally within their browser, and synchronize their bank accounts without ever having to share their username/password with our server.

Firefox 3 users do NOT need to install Google Gears or any other extension, since Firefox 3 has built-in support for client-side data storage (conforming to the new HTML5 standard)

Read more about secure synchronization via offline data storage.