Last night a completely unknown character announced on Twitter that he has a version of PwnageTool that jailbreaks iPhone 3GS on iPhone OS 4.0 beta 4, and today iH8sn0w confirmed that that program works!
iH8sn0w warns that version of PwnageTool could create problems because the bundles for iPhone OS could be incorrectly compiled and you could wake up with a bricked phone as soon as you use that program to jailbreak the phone.
So, if you have an iPhone 3GS that is registered in a dev account and you have the courage then you can try to make/use a custom ipsw made with that version of PwnageTool but do it at your own risk, you have been warned!
If there is someone brave enough to try, please leave a comment with a confirmation/denial of the functionality of the program.
The version of PwnageTool that I talked about can be downloaded from here.
UPDATE: I confirm that this version of PwnageTool successfully makes a custom ipsw of iPhone OS 4.0 beta 4. I have not yet tried to install that custom ipsw on my phone due to lack of time, but you can try, the creation process works.
