I myself also not pretty sure the exact number of leaked Jelly Bean OTA update for Samsung Galaxy S3 available in the web now since it just refuse to stop. In order to have anything arranged in systematic manner, I try to compile a list of leaked Samsung Galaxy S3 JB OTA update. It helps some of you who want to taste JB before the official OTA update from Samsung right after 29th event. Within the link, it shall provide the instruction to install/flash the OTA update as well as the changelog in the particular update. Please bear in mind, these OTA update are not official update provided to S3 users, flashing these OTA will void your warranty.
Leaked Samsung Galaxy S3 Jelly Bean OTA Update:
1. Samsung Galaxy S3 Android 4.1.1 Jelly Bean I9300XXDLG4 Test Firmware
3. Samsung Galaxy S3 Android 4.1.1 Jelly Bean I9300XXDLH7 [Latest]
I will update the list once another unofficial JB OTA update is available for Galaxy S3.