Redsn0w 0.9.6b5 Download Available
Redsn0w 0.9.6b5 has been released for download for both Mac OS X and Windows, and it allows you to jailbreak iOS 4.2.1 on iPhone. This new version of redsn0w is particularly valuable to those wanting to unlock their iPhone from baseband 05.14 and 05.15 because it prepares the iPhone 3GS and iPhone 3G for unlocking with ultrasn0w.
Redsn0w might also be considered easier to use since the application will automatically download the iPad IPSW 3.2.2 file from Apple rather than you having to do it yourself, meaning you only have to point at one IPSW file, which is your own jailbroken version.
Download redsn0w 0.9.6b5
You can grab the latest beta 5 version of redsn0w 0.9.6 for Mac or Windows:
Note: these links have been updated to download the rc16, the newest version of redsn0w.
Be sure to keep your device plugged in and powered via USB throughout the entire jailbreak process with redsn0w. For Windows 7 and Vista users, be sure to run redsn0w as Administrator in “Windows XP Compatability Mode” to avoid any errors.
The functionality of Redsn0w 0.9.6b5 is similar to PwnageTool 4.1.3 in that it allows you to upgrade to 06.15 baseband (from the iPad) which is vulnerable to the newly released ultrasn0w 1.2 unlock. This is currently the only way you can unlock certain versions of iPhone baseband.
Update: A new version of redsn0w has been released, you can now download redsn0w 0.9.6rc8, the new version is recommended for all.