Apple believes that the signal problems are related to a bad calibration of the baseband software in the new iOS 4.0, so on the Apple discussion forums several technicians have confirmed that there is a version 4.0.1 of iOS in the works that will be available this week next, most likely Monday. Phones generally display information about signal/battery/etc and iOS 4.0 seems to display the worst information so far, so Apple decided that everything could be solved with a software update.
It is curious that in the beta versions of iOS 4.0 there were no such problems, no one reported anything at all, everything worked ok but miraculously with the release of iOS 4.0 there were problems with the baseband calibration even though the baseband software is identical to the one in the beta versions. So I believe that Apple left this small defect to "bring out" the baseband exploits to the surface and will now release an updated software that also updates the baseband and will probably prevent the use of ultrasn0w with the new bseband.
When iOS 4.0.1 appears, please DO NOT INSTALL IT if you need jailbreak and decoding until you find out information from me that everything is 100% safe! If you try to install it before checking if everything is ok you might find yourself unable to jailbreak/decode your phone for a very long time because I doubt the Dev Team or anyone else will release a decoding software now.
