I tried updating to 4.0.2 tonight and it destroyed the software, sent it into recovery mode and I lost everything and have to restore. Just posting so people don't update I would advise against it because it isn't worth losing precious data that iTunes refused to back up before updating 
Update: after attempting to restore the software it went straight back into recovery mode and the process is now repeating. I will let you know if the seecond attempt to restore works. Again I did nothing to warrant this glitch and it worries me that I might have lost my data.
Update: after attempting to restore the software it went straight back into recovery mode and the process is now repeating. I will let you know if the seecond attempt to restore works. Again I did nothing to warrant this glitch and it worries me that I might have lost my data.