During the magical period of the Absinthe iOS 5.1.1 untethered jailbreak release, Apple came up with a new firmware for the GSM version of iPhone 4 which supposedly contains few bug-fixes. Now the build version of iOS 5.1.1 is 9B208 as opposed to the previous firmware version : 9B206.
If you haven’t upgraded to the new version then keep distance from this firmware as it’ll not work with the current Absinthe version. However, pod2g has stated today that a new version of Absinthe jailbreak tool is set for release very soon which will add support to this new firmware.
In the mean time, save SHSH blobs for the previous version of iOS 5.1.1 so that you can revert back to the previous version if something goes wrong in the near future. Following is the download link for the new build of iOS 5.1.1.
Download iOS 5.1.1 (Build:9B208) IPSW For GSM iPhone 4 [Direct Link]