LG Optimus G has been receiving Android 4.1 Jelly Bean in South Korea. The update, rolling out via both over-the-air and over-the-wire for customers with the LG-F180S on SK Telecom.
This update can’t be downgraded once installed. So to proceed follow the steps mentioned by LG Korea.
The new build upgrades the Optimus G from Android 4.0 Ice Cream Sandwich to Android 4.1 JellyBean.
Now question that when its going to roll out globally?
Source: LG Korea