if you’re waiting for untethered jailbreak, we advise you not to upgrade to iOS 5.1.1
Here’s step by step tutorial How to Jailbreak iOS 5.1.1 using RedSn0w:
Step#1 Download the latest version of RedSn0w 0.9.10b8b.
Step#2 Connect your device to your computer, place your device into DFU mode, and run RedSn0w.
Step#3 Go to Extras > Select IPSW > and point to your iOS 5.1 firmware for this device.
Step#4 Once RedSn0w successfully identifies the 5.1 firmware, head back to the main page of RedSn0w and click Jailbreak.
Step#5 Once it identifies the build, click Next where it asks you to install Cydia.
Step#6 Cydia will be installed, and your device will reboot. Upon reboot, place the device back into DFU mode.
Step#7 Perform a tethered boot via RedSn0w by going back to the Extras page and clicking Just Boot.
Step#8 Your device will reboot, and you will have a usable Cydia icon on your Home screen.
Remember this method will only work with iPhone 4, 3G, 2G, iPad 1 and iPod Touch 4G and 3G and there is no jailbreak for iPhone 4S, iPad 2 and iPad at the moment.