Today, Apple has released an updated version of iOS 5.1.1 only for iPhone 4 GSM. The build number for this iOS labeled as 9B208. Its not really sure why they have released it only for iPhone 4 GSM model but apparently it was released to fix some bug present in the software only for the specific model.
A few of the users have asked us whether they upgrade to this build and then jailbreak their devices and the answer is NO. That is the whole reason why are actually writing this post.
Apple has not updated the changes made in this build. Wait for some time and we would see whether this build is ok for the jailbreak or not. Make sure you have saved SHSH blobs of iOS 5.1.1 of your current firmware so you can always downgrade back if something goes wrong and you mistakenly update.
Those who do not care about the jailbreak and want to use updated Apple software can download iOS 5.1.1 for iPhone 4 build 9B208 from HERE.