No, No one is jailbreaking 4S yet because jailbreaking 4S is not exist.
Don't fall for it. Whoever said they can jailbreaking 4S is a lie. Check dev blog regularly or this forum and you will know immediately when it released.
go to the dev-teams blog or fallow musclenerd on Twitter he will report a jailbreak if it's legit. Others to fallow are ih8sn0w and chronic dev team. There are lots of others but if you get those your good.