But it doesn’t come as a major surprise as Dev team had released Redsn0w to jailbreak iOS 5 GM, and since Golden Master is the shipping version of the iOS software, we expected it to be possible to jailbreak iOS 5 public release as well.
Dev team has provided the following information on their blog about the new version:
For those of you who experiment with your own custom ramdisks using the -r command-line option, version 0.9.9b4 adds auto-detection support for iOS5. This is needed because iOS4 and iOS5 treat the root partition differently (it’s encrypted in iOS5). redsn0w will now upload the correct iOS5 kernel by itself, but it’s up to your own launchd to determine if it needs to mount using the old or new partition scheme.
redsn0w now also accepts both native and img3-encapsulated versions of files you provide via the -r, -k, and -d command-line options (do redsn0w -h to show all the available options).
Redsn0w 0.9.9b4 supports the following iOS 5 devices:
iPhone 4 (GSM)
Redsn0w 0.9.9b4 supports only a tethered jailbreak, except for iPhone 3GS with old bootrom which is untetherd. With a tethered jailbreak you need to connect your iOS device to the computer on every reboot. It still doesn’t support iPad 2, so it is unlikely to support iPhone 4S that was unveiled at Let’s Talk iPhone event.
Redsn0w does not preserve the baseband, so if you depend on Ultrasn0w to unlock your iPhone, you should not use Redsn0w. Sn0wbreeze for Windows currently allows you to preserve the baseband but Ultrasn0w is currently not compatible with iOS 5. Dev Team are expected to release an update after iOS 5 is released, however there is no ETA currently.
iH8sn0w has also confirmed that Sn0wbreeze 2.8 beta 8 that he had released for iOS 5 GM will work with iOS 5 public release:
It seems the Gold Master release seeded to Developers last week is the exact same IPSW that was released today.
With that being said, iOS 5 (Official) can be jailbroken (tethered) with the latest redsn0w & sn0wbreeze 2.8 beta 8.
We would recommend you to proceed with caution and advise you to wait until we receive some initial feedback from users. We would also recommend you to read the latest status update on jailbreaking iOS 5 so that you can weigh your option. If you plan to give it a shot, please don’t forget to take a backup of your iOS device.