According to a thread in XDA Developers forum, the Jelly Bean update is now officially being rolled out to the users of HTC One X in both Taiwan and Singapore. The 352.87MB OTA update is said to bring Android 4.1.1 ( Jelly Bean ) and HTC Sense 4+ to HTC One X.
As of now, there is still no information on when the Jelly Bean update will be rolled out to users of HTC One X from other countries.