First off, I'm definitely not new to JB/unlocking (I've had my 2G on T-Mobile for almost 3 years!). So I've been reading forums for hours and I can't get anything to work. I have an iPhone 3GS 3.1.3 with the new bootrom. Can I JB/unlock it to use iOS4? If not, I think I can still use Spirit to JB and ultrasn0w to unlock (while remaining of 3.1.3), right? Thanks.