An iOS developer called Pod2g has announced that he jailbroke iOS 5 few days ago and this jailbreak is untethered.
So far only one could boot his iPhone only through a semi-tether. Plus, there would be some restrictions and you would have to tether it to re-enable it.
The tests were initially done on a Third Generation iPod Touch with iOS 5. After further tests, Pod2g has confirmed that this jailbreak works with iOS 5.0.1 as well.
So far this jailbreak has been confirmed on the iPhone 4, iPhone 3GS, iPod Touch 3G/4G and Apple TV. The first generation iPad has also been included in the list. However, so far there is no confirmation whether it can run on iPhone 4S or iPad 2.
The release date of this jailbreak is not known but it is expected to arrive soon.
Source: Gadget Venue