Users of the iPhone 3GS who previously jailbroke their handset can upgrade to Apple's latest mobile operating system with PwnageTool 4.0.1, released by the iPhone Dev-Team. It is also available for the iPhone 3G and the second-generation iPod touch. The previous hack, PwnageTool 4.0, was not compatible with the iPhone 3GS.
The hack does not work for the iPhone 2G or first-generation iPod touch, both of which cannot run Apple's iOS 4. In addition, the third-generation iPod touch cannot yet be jailbroken.
Whether the hack will work with the iPhone 4, expected to be delivered today to many who preordered, remains to be seen. But 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, marking the first time ever that the company had enhanced the security of its hardware in the middle of a product line without a new model released.
A developer build of iOS 4 was jailbroken less than a day after it was released in early April. A member of the Dev-Team also took issue with Apple's claim that hardware restrictions prevented multitasking from being enabled on older iPhone hardware. In addition to existing unauthorized jailbreak solutions for multitasking, the hacking community has also released software to enable MMS functionality on the first-generation iPhone.
iOS 4 has a number of missing features for iPhone 3G users, namely the ability to multitask, as well as have wallpaper backgrounds on Home screens. Apple Chief Executive Steve Jobs reportedly said in an e-mail that the icon animation with backgrounds "didn't perform well enough" on the iPhone 3G.
But both custom wallpapers and multitasking have been available on the iPhone 3G for some time, thanks to jailbroken software that allows the handset to run in ways Apple does not allow.
The warranty-voiding jailbreak process allows users to run software not approved by Apple, which has no plans to allow users to install third-party applications downloaded from outside its sanctioned App Store. Hackers have created their own custom applications -- many free, and some for purchase from an alternative storefront known as Cydia.
Jailbreaking can also be used to pirate App Store software, one major reason why Apple has fought the practice.
In April, Jobs cited an unsanctioned pornography store available for the Google Android platform as a reason to not support unsigned applications. "That's a place we don't want to go," Jobs said, "so we're not going to."