Dev Team has gone the Apple way releasing beta versions of its redsn0w tool (version 0.9.7) and here comes the 4th edition of the beta that helps with you iOS 4.2.1. Strictly for testers, the windows version is also expected to be out soon. Apart from fixing a bug that crashed the tool occasionally, there is a relief for the testers. Here is the official words from the devteam:
The fourth beta is now available (testers ONLY please!). Starting with this version, redsn0w no longer requires you to install and run a separate program for the usbmux (this was a non-trivial procedure for many). It’s okay to keep that program running if you normally use it for ssh anyway.
The download link is: redsn0w_0.9.7b4 (OS X). If your device is currently jailbroken with one of the previous betas, please do a fresh restore first.
If you are dependent on ultrasn0w for unlock, keep away 🙂