To enable it , just long press on your home screen, tap Settings, and tap on the Allow Rotation Toggle ( which is under Home Screen section ) .
Along with Auto-Rotation feature , Google has also released icon normalization . It basically re-size apps icon and make them appear more consistent with other icons .
|Image credits - DroidLife|
You can Opt-in for Beta , by just going - Here and Download Latest Google app from Here .
via - DroidLife