Did you know you can jailbreak iOS 6 on A4 devices including the iPhone 4 and iPhone 3GS? Sure, it may be a tethered jailbreak, but for serious fans of Cydia this doesn't matter. As usual, if you are currently using any kind of baseband unlock you should steer clear of an iOS update and this jailbreak until further notice.
Before you begin, remember that this procedure will only work on the iPhone 3GS, iPhone 4 and iPod touch 4G. All of these devices have the Apple A4 processor. Start by updating your jailbreak-compatible iPhone to iOS 6. You can update your iPhone OTA or on your computer with iTunes. You will need to download the iOS 6 IPSW firmware file to your computer to jailbreak. Follow these instructions to jailbreak iOS 6 tethered: