While iOS 5.1.1 may have thrown jailbreakers a curveball, unlockers using the GEVEY Ultra S GSM with their GSM iPhone 4S will be happy to know it's safe to upgrade. According to online retailer ApplenBerry's Twitter feed, the GEVEY Ultra S GSM is compatible with iOS 5.1.1.
CDMA iPhone 4S or 4 models need to be jailbroken to use the Ultra 5.1 SIM interposer. There is no jailbreak for iOS 5.1.1 currently, but the GEVEY Ultra S does support iOS 4.1 and later (through 5.1). iPhone owners should not update to iOS 5.1.1 if they would like to keep their devices jailbroken.