This guide will show you how to jailbreak iPhone 3G/3GS/4 on iOS 4.1 using Redsn0w 0.9.6 beta2 on Mac.
WARNING: If you rely on your iPhone to be unlocked, to use it on an unofficial carrier, you should avoid this jailbreak. This jailbreak requires you to upgrade your firmware, via iTunes, which upgrades your baseband. The current baseband cannot be unlocked at this time, and cannot be downgraded. Use PwnageTool.
Step 1: Download iOS 4.1 and Redsn0w 0.9.6 beta2. (iPhone FW links here, Redsn0w Mac).
Step 2: Install the latest version of iTunes (iTunes 10.0.1).
Step 3: Update to this latest firmware (iOS 4.1) via iTunes.
Step 4: Launch Redsn0w 0.9.6 beta2 and point at the 4.1 IPSW.
Step 5: Click “Next” and watch as redsn0w is preparing jailbreak data.
Step 6: Check “Install Cydia” if not already checked, and click “Next”.
Step 7: Follow the onscreen instructions.
Step 8: Now you sit back and let Redsn0w do it’s magic! Once finished, your iPhone will restart automatically and you’ll have it jailbroken on iOS 4.1.