It seems that Greenpois0n might arrive anytime to jailbreak iOS 4.1 iPhone 4, iPod touch 4G and iPad. Chronic Dev Team has not shared ETA for iOS 4.1 jailbreak but their behavior towards his fans is indeed noteworthy. Even, after being nagged repeatedly by fans every minute, the team has posted an update about iOS 4.1 greenpois0n jailbreak that it is on track.
Those who do not know Greenpois0n is based on Shatter which is a low level bootrom exploit unlike userland exploit JailbreakMe, that can not be fixed by Apple without a new hardware release of iPhone 4 iPhone 3GS iPad and the iPod touches. Just firmware update will not going to patch the bootrom exploit.
The complete makeover of the Greenpois0n portal also hints towards the possible jailbreak release in few days. But, no ETA has been cited by hackers apart from confirming that all jailbreaks on iOS 4.1 need 2 exploits a tethered exploit and an untethered exploit.