Sorry to create a new thread on this; I've tried doing my own research, but keep finding conflicting data. About a month and a half back, a family member broke her unlocked iPhone via water damage. We're on T-Mobile. When I checked, I found that I couldn't unlock phones that had the 05.12.01 firmware. I understand that we now can. I'm looking to pick up a used 3G or 3GS off of Craigslist and unlock it for her. What new issues arise with the release of iOS 4? I'm hearing things about SHSH codes needed to downgrade that I'm not familiar with. Will I be able to unlock a used 3GS running iOS 4? Also, on my iPad, I noticed Cydia was giving me an option to save a machine identifyer (I'm guessing these SHSH codes I'm hearing about?), but I accidentally clicked the no button instead of yes (apparently, the buttons activate on Touch Down instead of Touch Up >_> ), and the option went away. How do I get that back? Thanks for any assistance, and I apologize for having to ask; but searching was running me in circles.