I read the forums extensively before updated and people were claiming that the feature to Turn 3G Off remained in this iOS 5.1 build for the iPhone 4S on ATT - but that is not true. This is necessary for me to run my business since the 3G signals in my area show 5 bars but literally do not work due to interference. If this is important to you, do NOT make the mistake that I did and upgrade to 5.1, just stay on the developer build of 5.1b where it is still an option to Toggle 3G. Damn it! UPDATE: Can iPad owners tell me if the toggle is there in 5.1?