I wonder about the other kind of the security. I doubt there's any serious protection against a rogue background-running application tracking your finger and gathering sensitive information, like keystrokes.

You know, check for what's the foreground process, notice it's a password manager or bank application (or even a lock screen would do, who knows, maybe user had reused the same PIN elsewhere), blast the speakers with ultrasound and wait for the typing-like movement patterns.