Ok, I consider myself somewhat tech savvy. I have been considering jailbreaking for some time and was going to do so until I spoke with an employee of a cell phone store. This was one of those little stores that fixes cracked iphone screens and jailbreaks/unlocks iPhones for a small fee. I had no intention of having him unlock my phone (3GS, iOS 4.2.1) but he was fixing my cracked screen so I inquired as to whether he would have any difficulties jailbreaking my phone. He told me that he could do it but that it would be a risk. I asked him what that meant and he told me that after jailbreaking I could end up being tethered so that my phone would not boot up (if switched off) without being connected to a computer. He said that the serial number of my phone indicated that it was from week 24 of 2009 and that while, in theory, the jailbreak would work, that there was a chance it would be tethered. Furthermore, when I asked him whether it would be possible to restore the phone in the case that it was, indeed tethered, he said no. Now, it was my impression that a jailbreak could be rolled back and that the phone could be restored to factory settings at any time. But he's now raised some doubts in my mind. What do you all think? Is there any chance of my 3GS being tethered if I jailbreak? What jailbreak software would be most recommended for my phone? Thanks very much.