So why was the Android 4.0 first made available and then apparently pulled? One AT&T customer decided to discuss the matter with an AT&T rep via a Live Chat. And during this chat, the rep said that the update has been delayed due to "Technical Reasons". There is some speculation from Samsung and AT&T reps that the update will be attempted again this coming Saturday, but during the Live Chat, the rep said that he/she had no new details because the update was still in the process of being tested.
Some who managed to download the update before it was pulled are complaining about lag, which might be why the update was pulled to begin with. Those with the device can wait until Saturday and see if they have the opportunity to try again.