Yay there's already a topic about this so I don't have to make one. I have a JB 3.1.3 and right now I'm trying to go from that to the iOS4 today. The only thing that I don't really like right now about the process is I have to save all pictures, songs, and videos to my itunes library and then resync them once the update's done. And with 30 or so Apps, 200 plus songs, and 140 pictures I have a feeling it's going to be a long night.