Notcom has released updated TinyUmbrella with support for iOS 5.1.1 (Build 9B208) which is released by Apple for iPhone 4 GSM users.
Download TinyUmbrella v5.11.01 for Mac
Download TinyUmbrella v5.11.01 for Windows
See also:
Sn0wbreeze 2.9.5 Untethered Jailbreak for iOS 5.1.1
Absinthe 2.0.2 Untethered Jailbreak for iOS 5.1.1
Download iOS 5.1.1