Android 4.2.2 (which I'm currently running on my Nexus 4) has support for the notion of authenticated adb. This is supported in adb 1.0.31, and when adb tries to connect to the phone, the phone will show as "offline". The phone will present a prompt asking if its ok to connect the indicated host. Until the user acknowledges the prompt, the host will be unable to connect vi adb. This makes adb dramatically more secure.