
The iPhone dev team is continuously releasing updated versions of their jailbreak tool Redsn0w with including some new features so according to their official blog, the latest Redsn0w 0.9.11b4 completes the tethered jailbreak support for 5.1.1 on A4 devices and earlier, including proper “Stitching” and “Custom” creation of NO_BB IPSWs.
Download Redsn0w 0.9.11b4 for OS X
Download Redsn0w 0.9.11b4 for Windows