they are focusing on security in android 4.2
This is a list of new stuff in the 4.2 dump, not a list of "confirmed for 4.2" features. Anything could be cut or not fully implemented by the time 4.2 rolls around; similarly to how bits of Android are currently multi-user aware, yet multi-user functionality isn't accessible. Some of this stuff may make it to 4.2, but probably not all of it. Got it? Good.
Now, get ready for a HUGE security push. I recently revealed the Play Store was getting "App Check," a client-side malware scanner, and Google already has "Bouncer" a server-side malware scanner, but they aren't stopping there.
SELinux
This image has been resized. Click this bar to view the full image. The original image is sized 668x353.
Security-Enhanced Linux is a set of kernel add-ons and user-space tools first started by the NSA that brings mandatory access control to Linux, which basically means user programs and system servers only run with the minimum amount of privileges they need to function. Unmodified Linux uses discretionary access control. Users can grant high levels of access to files they own, and malicious software can do anything it wants with the files and controls the user has access to. If you run that malicious app with root privileges, it now has access to everything.
In SELinux, there is no concept of a root user. Security policy is defined by an Administrator and applied to every process and object, and nothing can override it. This means the potential damage a malicious program can cause is minimal. Basically, SELinux is serious lockdown-mode for the hyper-secure enterprise crowd.