If you have a European or Asian model One X (read: Not AT&T), start frantically hitting that check update button - it's
peanut butter jelly Jelly Bean time. We're hearing from multiple sources that HTC is beginning to roll out Jelly Bean to the One X in various regions today.
This update brings Android 4.1.1 and Sense 4+. Expandable notifications, Google Now, and some fairly minor tweaks like a new Gallery app in Sense are in tow. Sense also now has wonky holo blue highlights throughout the OS, so that's cool, I guess.
If you can't see the update on your phone, we've got a pretty easy explanation: your particular CID (a regional hardware identifier code, typically by country or carrier) hasn't had Jelly Bean rolled out to it.