Looks like our friend @pod2g was successful with the untethered jailbreak on an iPhone 4 running iOS 5.0.1! (12/11/2011)
However if you want to preserve your baseband, @pod2g suggests that you’d want to hold off it for now.
Great news for those waiting for the untethered jailbreak. Now here’s hoping that we get one for our A5-device folks.