If you’ve already installed rocky-racoon, don’t bother reinstalling it unless you’ve had problems and would like to try a different tool. The underlying untethered jailbreak (rocky-racoon) is identical to what is already installed by last week’s tools like Absinthe, cinject-0.5.3, and the rocky-racoon Cydia package — only the injection method offered by the above tools differs.

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).
We’ve also added a new redsn0w feature specifically for those who got in on the SAM unlock: you can now include your SAM tickets as part of your initial ramdisk jailbreak of iPhone4 or earlier, or alternatively you can upload your SAM tickets to any device after its been jailbroken. redsn0w accepts either the individual SAM activation ticket plist file, or the entire zip file created by redsn0w’s “Backup” button. As usual, redsn0w continues to cover all of its previous jailbreaks and untethers (so redsn0w-0.9.12b1 covers everything from 5.1.1 all the way back to 4.1).

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).