This feature allows you to see at a glance whether the Web site you’re visiting has supplied information about their identity, who has verified that information, and whether they protect your information from eavesdroppers. You can access the site identity for any web site by clicking the site’s icon on the left edge of the location bar (or by typing Shift-Tab-Enter).
About One-Click Site ID
Firefox 3 contains a new site identity button to help you know who you’re connecting to when online.