The second iOS 5 beta was seeded to developers last week and it looks like Apple has stepped up their game to combat jailbreaking. The latest beta also takes measures against downgrading.



From PCWorld:

According to a blog posted by iPhone Dev-Team (the hacker group responsible for PwnageTool and Redsn0w jailbreak tools), Apple has altered the iOS boot sequence to require a signed authentication ticket- which is yet to be (and may never be) hacked. This renders current "untethered" jailbreaks, used in tools such as PwnageTool and Redsn0w, effectively useless for iOS 5 at the moment. There is another tool that uses an exploit earlier in the boot process called limera1n that will still function for the foreseeable future, but is a "tethered" jailbreak.

  Will iOS 5 Put An End To Untethered Jailbreaking?