The iPhone Dev-Team has released updates to RedSn0w and PwnageTool that bring support for the iOS 5.1.1untethered jailbreak.
RedSn0w 0.9.12b1 supports untethered iOS 5.1.1 jailbreak for all devices:
iPhone 3GS
iPhone 4S
iPad 1
iPad 2
new iPad 3
iPod Touch 3G
iPod Touch 4G
PwnageTool 5.1.1 allows to create custom firmware and preserve modem version for unlock with ultrasn0w or Gevey. PwnageTool 5.1.1 supports all A4 devices:
iPhone 3GS
iPhone 4
iPad 1
iPod Touch 3G
iPod Touch 4G
Apple TV 2G
You can download RedSn0w 0.9.12b1 and PwnageTool 5.1.1 .