The iPhone Dev-Team has now updated the Redsn0w 0.9.7 untethered iOS 4.2.1 jailbreak tool to beta 6, primarily fixing Skype related issues that arose ever since the beta 1 of Redsn0w 0.9.7 was launched.

The Team has issued an anti-piracy plea in order to refrain people from pirating Apple software:
Please do not pirate the 4.2b3 IPSW! Only those enrolled in the iPhone Developer program have legitimate access to that IPSW using these links (the links won’t work unless you’re a legit developer currently logged in).

The iPhone Dev-Team says:
The sixth beta is now available (testers ONLY please!). This version fixes Skype (and as expected all along, the Skype issue turns out to be unrelated to sandbox patches).
Unlike the last few betas, you can freely run beta6 over beta5 without a problem (but for testing purposes, we’d really like people to try both ways….from stock, and from already jailbroken). If all you want to do is fix Skype and you’re already untethered using beta5, just run beta6 and deselect every checkbox.
The Team has also added:
Now that the sandbox, Bluetooth, and Skype issues are fixed, our next priority is porting Monte back to 4.1. We’ll also try to make the Windows version less painfully slow.
What porting the “Monte” technique back to iOS 4.1 means is that users will be able to untether the iOS 4.2.1 jailbreak on their iOS devices, eliminating the need to have iOS4.2b3 SHSH blobs saved on Cydia.
Just recently, the iPhone Dev-Team released beta 5 of Redsn0w 0.9.7 eliminating sandbox and Bluetooth related issues, and with the release of beta 6, the Skype related issues are eliminated as well. Hopefully the Windows version of Redsn0w will be coming soon right after the iPhone Dev-Team is finished fixing the performance related issues the Windows version is facing.
Download Redsn0w 0.9.7b6 from here.