After releasing Redsn0w 0.9.8 b1 for Mac users, MuscleNerd, the key member of iPhone Dev Team has just released the same software for Windows Machines. It is still tethered jailbreak and meant for Developers only who are registered with Apple’s Developer program.
Redsn0w 0.9.8 b1 can jailbreak iOS 5 beta version on iPhone 4, iPhone 3GS, iPad 1, iPod Touch 3G and iPod Touch 4G.
UNLOCKERS AND THOSE PRESERVING THEIR UNLOCKABLE BASEBANDS SHOULD STAY FAR AWAY FROM THIS! You will very likely lose your unlockable baseband if you try to install iOS 5.
THIS JAILBREAK IS INTENDED ONLY FOR DEVELOPERS OF JAILBROKEN APPS! There are just too many broken components (Apple’s official apps, 3rd-party App Store apps, Cydia apps, MobileSubstrate apps, etc) for this to be useful to anyone but those truly looking to fix bugs in their iOS 5 jailbroken apps. (Seriously!)
THIS REDSN0W WILL NOT HACTIVATE 5.0b1! You need to be an iOS developer with a registered UDID to get past all the new activation screens. PLEASE DON’T PIRATE APPLE SOFTWARE! Only registered devs with Macs can develop iOS applications, and only those people will have legitimate access to the beta IPSWs.
THIS IS A TETHERED JAILBREAK ONLY! No new exploits are being exposed with this jailbreak (it uses geohot’s limera1n bootrom exploit), but that comes at a cost. You will need to use redsn0w to “Just boot tethered now” to be able to use many things, including Cydia and Safari. If you see a white icon for Cydia, or if Cydia or Safari crash when you open them, it’s because you didn’t boot tethered.
IF YOU HAVE THE 06.15 BASEBAND ON YOUR 3GS…this redsn0w will get you past the iTunes restore error you’ll get when using the stock IPSW (nobody other than those with the 06.15 baseband should be going anywhere near the stock IPSW!).
The way redsn0w works, you will very likely be able to use this on upcoming iOS5 betas, just by continuing to point redsn0w at the 5.0b1 IPSW. So keep that IPSW handy!
The step by step guide to jailbreak iOS 5 for iPhone, iPad and iPod Touch is posted here which is same for both Mac and Windows users.