While DevTeam is still working on an update to ultrasn0w for the software unlock, Loktar_Sun after tinkering with the SAM method which is originally used to activate iPhone on any carrier or push notification from iTunes now unlocks a JailBroken iPhone 4 & iPhone 4S. The SAM method was developed by Sam Bingner (@sbingner) for a separate purpose, but it turned out to be one of the simplest method to convert a temporary software unlock into true one.
MuscleNerd has confirmed SAM unlock method to be working on his iPhone 4S. He was being able to run T-mobile without issues. However, you need to have the particular carrier sim inside for the unlock process to proceed specifically for that sim. As per Sam Bingner, the unlock could also work for people who are on iOS 5.1 with tethered JailBreak. Until iPhone hackers releases iOS 5.1 untethered JailBreak for all devices, you can give it a shot.
Even though SAM creates a valid ticket for one Sim, you could create tickets for the multiples sims and then save each of them for the use. Also, don’t forget to save the unlock activation ticket from this trick, it is likely to be useful for a longer time. Needless to say, Apple might fix SAM method in the next software update. For more info on how you could perform the unlock on a JailBroken iPhone, follow the SAM tutorial from here.
If you come across any issues while performing the unlock, let’s know in the comment section.