I have an older version of jailbreak. I know how to upgrade to the latest jailbreak but the problem is that I have my iphone 4 unlocked with SamPrefs, a method that was available only for a short time when it released. I'm afraid if I upgrade to a newer jailbreak, SamPrefs will not work anymore, losing my unlock for T-mobile. Does anyone have any insight on the matter? I want to download apps from my appstore but many nowadays require a newer iOS.