Currently, the iOS 4.1 Jailbreak is being worked on by the chronic development team.
The codename of the 4.1 Jailbreak is Greenpois0n.
There are no news of when is the release date,but is definetely being worked on. This exploit is a bootrom exploit,meaning even if Apple comes out with a new firmware,it can still be jailbroken.
The offical website is http://www.greenpois0n.com
Image from http://www.greenpois0n.com
Coreness will update on the latest greenpois0n news.