While working on the next untethered jailbreak for iOS 4.2.1, the iPhone Dev team has figured out that Apple team hasn’t stopped serving iOS 4.1 firmwares to users. Recently developed Redsn0w 0.9.7b6 has capabilities to bring untethered jailbreak on iOS 4.2.1 based iDevices.
Today, they have publicly announced that Windows version of Redsn0w will be out for those who are waiting for untethered iOS 4.2.1 jailbreak. Here’s the official update from the Dev team -
Since Apple still serves the 4.1 IPSW (not blobs!), we’ll do a Windows redsn0w release for untethered 4.2.1 via Monte-4.1

In another update, Dev team has warned everyone as untethered jailbreak for Windows will not be as smooth as previous tools.
Please don’t complain too loudly about how slow it takes
The Win version uses filesystem instead of RAM: slow!

More updates coming soon. Stay tuned.
