This is an intentional change because we believe the padlock icon is misleading and potentially harmful. Users were being told to "look for the padlock" as a s

This is an intentional change because we believe the padlock icon is misleading and potentially harmful. Users were being told to "look for the padlock" as a sign that a transaction was secure, when really it means no such thing. It's important that users actually verify the identity of the site -- a "secure" (encrypted) transaction is no good if it's a secure connection to a malicious site. The new security UI in Firefox is designed to emphasize identity, rather than just encryption.