T-Mobiles support page for the device lists the update. They do make an important note though, if you are version .10 or .7, you are on the most current software version. This update weighs in at 30MB’s. That package size is large enough to have some changes inside, but say there isn’t a difference between the two. Not sure how that can be possible. When the wife gets home this afternoon I’ll snag her One S and see what version she is on and if I can upgrade it or not.
Hopefully HTC has Jelly Bean nearly ready with T-Mobile for the One S. After all, a previous message from HTC had stated that October was the month for it to start. That was a general statement though and we all know that carrier updates in the states take quite a bit longer usually.  It sure would be a nice Christmas present for many people if it happens soon though.
Source: T-Mobile Support via Tmonews