Just a quick heads up! Redsn0w 0.9.7 beta was out yesterday to bring untethered jailbreak for iOS 4.2.1 but some of our readers has reported that usbmuxd process is not working with them. Also Windows users were left behind and couldn't convert their devices to untethered jailbreak.
Though, the iPhone Dev Team is working hard on releasing new betas so in a new tweet today confirming that Redsn0w 0.9.7b4 will incorporates usbmuxd so you shouldn't worry anymore. In the same tweet, the iPhone Dev Team has confirmed that after finishing this task, the next version (Redsn0w 0.9.7b5) will include the Windows version.
tman15555: @redsn0w_testers when will the version that incorporates usbmuxd be realeased? I keep on getting stuck on installing bundles
redsn0w_testers: @tman15555 that version is next...and if that's successful, we should be able to expand to Windows testers after that