Few hours ago an update was released for untethered jailbreak redsn0w 0.9.10b2 ios 5.0.1.
This update is needed to solve various problems with iTunes error.
Re-run the new version of redsn0w jailbreak mode on your current iPhone OS 5.0.1 already jailbroken (even PwnageTool), taking care to de-select “Install Cydia”. Always make sure to do a reboot and then turn off your device before running redsn0w.
I have not tested so always proceed with caution:
here are the links: