The iPhone Dev-Team has successfully jailbroken Apple's recently launched iOS 4 for the 3GS, 3G and second-gen iPod Touch.
However, PwnageTool 4.0.1 does not work with the iPhone 2G, first-gen iPod Touch or iPod Touch 3G.
"Currently, PwnageTool [for 3GS only functions with] previously jailbroken devices [that have an] old bootrom," Dev-Team explained in an official blog post.
"If you have a Jailbroken iPhone 3GS with the OLD BOOTROM and you DID NOT use Spirit to jailbreak then you can create the ipsw with PwnageTool 4.0 and restore with your jailbroken recovery mode. If you have an iPhone 3GS with the NEW BOOTROM this is NOT supported by PwnageTool 4.0 PwnageTool 4.01."
The Dev-Team also instructed 3G owners with a jailbroken iPhone at 3.1.2 (NOT Spirit) to create the ipsw with PwnageTool 4.01 and restore from recovery or DFU mode.
"If you have an out of the box iPhone 3G you should restore using a PwnageTool 4.01 ipsw using DFU mode...And if you have a Jailbroken 3.1.3 iPhone 3G it is very possible that this can fail from recovery mode, if this failure happens you will need to restore using DFU mode.
"As an alternative to PwnageTool, you can use redsn0w on iPhone 3G (on both Windows and Mac)."
Meanwhile, AppleInsider's Sam Oliver questioned whether the latest iteration of the hack would work with the iPhone 4.
"It is likely that the new handset will include enhanced security measures designed to thwart hackers. Late last year, Apple became more aggressive against jailbreak attempts when it silently updated the BootROM in the iPhone 3GS," wrote Oliver.
"[Nevertheless], a developer build of iOS 4 was jailbroken less than a day after it was released in early April...And in addition to existing unauthorized jailbreak solutions for multitasking, the hacking community also released software to enable MMS functionality on the first-generation iPhone."