It has now been confirmed that LG has begun pushing out a 575 MB Jelly Bean update to the Optimus L9. The update will be available via over-the-air ( OTA ) update notification as well as LG Update tool. This update will bring the a new customizable lock screen, new notifications field, Project Butter and some other new features to the LG Optimus L9. If you’ve not received the update, you can manually download it by going to Settings > About phone > System software updates.
This update comes in several phases, so you may have to wait a few of days or even weeks for the update to hit your device – especially those in the U.S.
Source : xda-developers