I received the ultra-sim from unlockcellular yesterday, and commenced with the jailbreaking this morning. It went well until I got to updating to 1.1.2. The update failed with "unkown error 1602" I couldn't find any threads that indicated where anyone had found a difinitive solution to this problem, so I figured we might need one. Its fairly simple. Use iTunes 7.5 for the update. Now I said fairly, because from my experience and what I saw of other posts with this error, an updated installation from 7.4 to 7.5 will get the same error. When I tried to do the update from my ancient Pentium III laptop with usb 1.1 that had only ever had 7.5 installed it worked like a champ. So, you either need to find a way to totally remove the older versions of iTunes, and the Apple Mobile device drivers, or find a machine that has never had iTunes installed on it. There is also an Apple tech note on this issue;

http://docs.info.apple.com/article.html?artnum=306084

I'm also happy to say that the jailbreaking and installing the ultrasim is working great on Vodaphone Italy.