MuscleNerd of iPhone Dev Team has confirmed that an updated version of Ultrasn0w unlock will be released in the next few days to fix signal bar issues on iOS 4.3.1 compatible iPhones, running on the old baseband.
MuscleNerd: The 4.3.1 issues (signal bars, etc) are fixed http://is.gd/OYktXf but need a few days to test all devices + FW (again: not a new unlock!)
However it is to be noted that this release of Ultrasn0w wont be a new unlock for iPhones with newer basebands, instead, it will only fix the compatibility and signal bar issues on the existing devices, which are jailbroken (with preserved basebands: 01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00) on iOS 4.3.1 using PwnageTool or Sn0wbreeze.
MuscleNerd: It’s probably confusing, so worth repeating: this isn’t a new unlock. It’s a compatibility fix for current unlockers only
MuscleNerd: (and for those retaining older baseband for resale value even though they don’t use the unlock themselves)
We will keep you updated as always, stay tuned for more. (via Twitter)