Chronic Dev Team member Dustin Howett posted a video of a jailbroken iPhone 4S on YouTube a few days ago. The video shows the A5 device running Cydia after it has been powered off and on. Howett also proves that Siri still functions by asking her to check the weather.
iPhone hacker and Corona developer pod2g republished the video on his blog saying that a release is only a few days away. It only took pod2g nine days to release his A4 untethered jailbreak after he posted a similar video of a jailbroken iPhone 4 on YouTube.
While it seems like the launch of an untethered iPhone 4S jailbreak is imminent, pod2g did promise a public release a few weeks ago, but did not deliver. In fairness he said "with some luck" that an iPhone 4S jailbreak would be available in "a week." That tweet was sent around 12 days ago.
This will be the first public release of an untethered jailbreak for devices using the A5 chip. The iPhone 4S in the video is running iOS 5.0.1.