iPhone Dev Team has released Beta2 of redsn0w 0.9.7b2 for untethered iOS 4.2.1 jailbreakthat fixes all the native app crashes (including Task switcher). Bluetooth is still disabled. Updated redsn0w is said to jailbreak iPhone 4 and other fourth generation devices such as the iPod Touch 4 and the iPad.
The second beta is now available (testers ONLY please!). This version should fix all the native app crashes (including Task switcher). That’s the only change in from beta1…. is still disabled. If you had trouble using the usbmuxd in beta1, please wait until we incorporate that into redsn0w itself (i.e. don’t bother trying this beta2, just wait for the integration).
Download Redsn0w 0.9.7b2 for Mac OS
Download redsn0w 0.9.7b2 for Mac OS X. You can follow guide to untether your iOS 4.2.1 jailbreak.