iPhone Dev Team member MuscleNerd has confirmed that an untethered jailbreak for iOS 5.1.1 will be released this week. Over the weekend, pod2g tweeted that "something big" was going to happen at the Hack In The Box security conference in Amsterdam being held May 21 through May 25. He later added that a public release was only a few days away. On Monday, MuscleNerd released an iOS 5.1.1 "info sheet" that revealed how the iPhone 3GS and iPod 3G made the jailbreak cut.
The upcoming jailbreak will be released via multiple tools just like the iOS 5.0.1 jailbreak was (e.g. cinject, RedSn0w, and Absinthe). All current iOS devices will be supported except for AppleTV 3. For a complete list of supported devices click here. MuscleNerd's "info sheet" is posted below.