The HTC One X has been rooted before it's official release thanks to Android hacker Paul O'Brien. With his Superboot method, any One X that has S-Off, or has been unlocked via the official HTCDev bootloader tool will be subject to this method, which uses the fastboot protocol to boot an insecure image that automatically loads the files needed for a system-wide root. It's easy, it works well, and should make for a simple way to root your phone once we get the One X in our hands, as long as HTC supports the device at launch with their bootloader tools.
Which is where things get a tad more complicated. Paul developed this method using a phone that was factory S-Off, which we shouldn't count on seeing in the wild. Traditionally, HTC has waited a while before providing access to their bootloader unlocking tool for new models, and without it we won't be able to boot with the Superboot image. Couple this with the different version we'll see here in the states for AT&T and things get a little more complicated.
As usual, we all appreciate the work Paul does with new phones, and are looking forward to having a fully rooted and unlocked HTC One X in our hot little hands. Let's just hope that HTC supports unlocking the bootloaders in a timely fashion, and that Paul's work helps developers for the AT&T model as well.