Pod2g's untethered jailbreak is just a few days away. He has even gone as far as to let everyone know that it is safe to upgrade to iOS 5.1.1. Although if you need to keep your baseband I'd still avoid it at the moment. Absinthe 2.0 and the new version of Redsn0w won't support iOS 5.1. That means you have to upgrade to 5.1.1 if you want the latest Jailbreak. Just remember to backup your idevice before you upgrade. If your iDevice is already jailbroken, backup your SHSH blobs using TinyUmbrella and don't upgrade until the new jailbreak is out in the while.