While no Android OEM has been particularly good with upgrades, HTC has been one of the best manufacturers when it comes to rolling out the latest Android versions as quickly as possible and on as many devices as possible.
The only other manufacturer that I can think of that may have been better than HTC is Asus, but Asus only has a few products on the market, and it started on the new Android 3.0/4.0 codebase, which made upgrades a lot easier. This is why we’ve seen Asus upgrade their Honeycomb tablets within two months of the ICS release, while all the others took six months or so to come out with either new ICS devices or upgrades for the older ones.
HTC seems to be working hard to upgrade their devices to Jelly Bean as soon as possible, once again. The leaked picture above from the Australian Telstra carrier shows that HTC is “preparing” the Jelly Bean upgrade for the HTC One XL (LTE version of the HTC One X) and the HTC One S.
The release date was not announced, so probably HTC has just started working on it, but since the Jelly Bean code changes are not that huge, I think we can expect a timeline of two months or so, just like we had when moving from Froyo to Gingerbread. However, this should only be true for the most popular devices of HTC and other manufacturers. For the other ones, the speed of the rollout will depend on how manufacturers prioritize development resources.