iOS 5.0.1 was released - and, chances are, you may be looking to downgrade to an earlier version of iOS for one reason or another
Downgrade the Baseband 4.11.08 to 4.10.01 and Unlock the iPhone 4. With iOS 5 Apple has not only closed the gap for a untethered jailbreak
iOS 5 is not SHSH blobs at the time, was already expressed by the Dev Team, that to save the current option, no downgrade
a way was found to perform a downgrade without secure SHSH blobs. This method is explained to downgrade from 4.3.5 / 4.3.4 to 4.3.3
This will help you downgrade the iOS 5 to iOS 4.3.3/4.3.2. If iOS 5 is still beta, it's not for nothing, its development is not finished yet. many bugs
This Guide is to downgrade iOS 4.3 to 4.2.1 iOS and error 1013 in iTunes 10.2.1. Currently it is possible to downgrade iOS 4.3
Installous has been updated to version 4.3 to support the new iOS 4.3. Your device must be jailbroken on iOS 4.3
Follow the instructions posted below to downgrade iOS 4.3 on iPhone 4, 3GS, iPod touch and iPad to iOS 4.2.1, 4.1, 4.0.x.
This method restore your device on the official firmware using iTunes which was otherwise not possible on iPhone's 06.15.00 baseband.
If you upgraded to iOS 4.2.1 and now want to downgrade back to iOS 4.1 / 4.0.2 / 4.0.1..iOS 4.2 on iPhone 4, 3GS, 3G, iPod touch and iPad
To ensure that these directions to work it's important to have in the past jailbroken on an prior firmware model and opened Cydia permitting it to save lots of your SHSH...