Apple has released iOS 5.1.1 for iPhone 3Gs, iPhone 4, iPhone 4S, iPhone and iPod touch 3rd and 4th generation. If you want to in the future use of an untethered jailbreak on iOS 5.1, it is wise not to install this update. iOS hacker pod2g has not yet been announced whether his exploits can also be used for a iOS 5.1.1 jailbreak. So it would be but so can some leak fixes that Apple has so new exploits to be found.
Even if you currently have a jailbroken iOS device is not wise to keep your device to update this because you will lose your jailbreak touch.