It looks like the Dev Team is working day and night on the RedSn0w untethered jailbreak for iOS 4.2.1. They first released the tool on Sunday but it came with a few major issues. They quickly released a second beta version last night and now they are shipping a third version that supposedly fixes even more bugs.
RedSn0w 0.9.7b3 should fix problems with FaceTime, WinterBoard, and embedded videos in iTunes…
The third beta is now available (testers ONLY please!). This version extends the fix made in beta2 over to the non-GUI programs too (like the daemons that handle media content). That should cover things like Facetime, Winterboard themes, and embedded videos in iTunes. If you had trouble using the usbmuxd in previous betas, please wait until we incorporate that into redsn0w itself (i.e. don’t bother trying this beta3, just wait for the integration).
Even though the jailbreak is getting more and more stable, I want to remind you that it is still in beta, which means you should stay away from it unless you feel very comfortable with the required steps (see our tutorial here).
You may download RedSn0w 0.9.7b3 from our downloads section.