Yesterday Dev Team released redsn0w 0.9.10 beta 6, a program with which all owners of iPhone 3GS/4, iPad or iPod Touch 3G/4G terminals can perform a tethered jailbreak for iOS 5.1 and here I published a tutorial who will teach you how to do this. Also yesterday, the Dev Team specified that people who update to iOS 5.1 while keeping the baseband of the iPhone terminal intact will be able to unlock using ultrasn0w, but they mentioned that the new version of ultrasn0w will be released in the following days. Basically, if you update to iOS 5.1 now, you will not be able to unlock using ultrasn0w because the version in Cydia is not compatible with iOS 5.1.
It is not known when the new ultrasn0w will be released, but as soon as it is available in Cydia I will let you know. The new version of ultrasn0w does NOT decode new basebands, so only the old ones remain, released BEFORE iOS 4.1.
