The iPhone Dev Team has updated PwnageTool, redsn0w, ultrasn0w, and cinject to support an untethered jailbreak under iOS 5.1.1. If you've already jailbroken with Absinthe and aren't having any issues, you can stay where you are. But if you ran into issues with Absinthe or need to unlock and maintain your baseband, these updates are for you.
The PwnageTool update will allow unlockers to update to iOS 5.1.1 without updating their baseband and losing their unlock. So if you depend on ultrasn0w for an unlock, you can use PwnageTool in order to upgrade safely now. PwnageTool will also support an untethered jailbreak on the Apple TV 2.
PwnageTool also avoids any possible sync issues, but again it applies only to A4+earlier devices. If you unlock your iPhone with ultrasn0w or a commercial method, you must use PwnageTool to avoid updating your baseband otherwise you’ll lose the unlock. PwnageTool will also jailbreak+untether the AppleTV2,1 5.0_2B206f (unless you customize the IPSW further, you’ll have just basic SSH access to the device).
redsn0w has been updated to version 0.9.12b1 and supports all A4 devices, meaning the iPhone 4, and earlier. So again, if you had issues using Absinthe on your iPhone 4 or earlier device, I'd recommend giving redsn0w a try.
redsn0w allows owners of A4+earlier devices to install rocky-racoon two different ways:
-backup/restore method similar to Absinthe and cinject
-its traditional limera1n-based ramdisk install. If you have a lot of media on your A4 device (music, movies, TV shows, etc), then the ramdisk method is preferrred because it avoids any possibility of later problems related to syncing to iCloud (including Photo Stream and Music Match). The ramdisk method is not available for A5 devices or later because limera1n can’t be used. If you’d like to use redsn0w’s ramdisk method, just be sure to put the A4 device in DFU or Recovery mode before starting redsn0w (otherwise it will immediately start to use the backup/restore method).
Cinject includes some compatibility updates and bug fixes over the 0.5.3 version but no major changes.
ultrasn0w 1.2.7 will allow you to unlock your iPhone after jailbreaking and updating with PwnageTool 5.1.1 assuming you have an eligible baseband. Once you're done updating just run the ultrasn0w package from Cydia to unlock.
If you're not sure whether or not your device can be jailbroken, how to jailbreak, or need to grab the download links for any of these tools, you can do so via the links below.
Source: iPhone Dev Team