As you might know, Apple introduced a new version of iBoot to fix a security vulnerability that prevents the 24kpwn exploit .Eric McDonald, a member of the DevTeam, said in a telephone interview with wired.com that there is nothing to fear about, because even on the “new iPhone 3Gs” we will be able to run the Jailbreak.
It’s not going to be impossible to jailbreak even if the exploit we used is gone
He explained that the exploit currently called 24kpwn can’t be used on the new devices. This exploit was only used to simply boot the device in order to launch the iPhone after jailbreak.
You can pefrome a “tethered jailbreak” on the new iPhone 3Gs, which means that you will have to connect the device to the computer in order to be able to start it.
The “hassle” of having to switch connection to the computer will not last long because the DevTeam has stated that they will find a new exploit. Even the iTouch 2G has an updated version of iBoot and,it can be started without tethered jailbreak.