Quote (IPhone Dev Team):
The b2 version of redsn0w includes the launchctl-related fix by @planetbeing as mentioned by @saurik here and here. As usual, you can just re-run redsn0w in jailbreak mode over your existing 5.0.1 jailbreak (even a PwnageTool one), making sure to de-select "Install Cydia" if you do. Always be sure to do a controlled "slide to power off" shutdown of your device before running redsn0w.