I have a strong feeling that HTC is working hard on it and it'll be done "soon" for the International Tegra 3 version, but then they'll have to make it for the Snapdragon version (stuff is different), AND we'll have to wait for AT&T to approve it and push it out. That'll probably be the bigger hold-up honestly.
I'd say within a few months. Some people are impatient but so far I LOVE my One X just teh way it is. JB update will just make it even better but in no rush. It's a power house of a phone and glad I went with it over the SG III.