In Pictures: Android 4.2 - A visual guide to what'...
Worried about security? Google's got your back: Android 4.2 includes a new multilayered security system that scans apps loaded onto your phone in real time. If you opt into the service, the system looks for malicious or potentially harmful code every time a new program shows up; it alerts you if there's any cause for concern.
(The new feature focuses on apps obtained from third-party sources; apps downloaded from the Google Play Store have been automatically scanned and evaluated on the server side for some time.)
The beefed-up security setup also watches for suspicious texting activity from installed applications; if one of your apps tries to send a text that'll cost you money, the system warns you before the message is allowed to go through.
In Pictures: Android 4.2 - A visual guide to what's new