We knew they were working on it, and here it is: proof of an iPad running iOS 4.2 beta 3, and MobileTerminal app installed on it. The iPad is, consequently, jailbroken.
The screenshots were posted by well-known hacker @iH8sn0w a few minutes ago, and they confirm the theory that a jailbreak for iOS 4.2 is in the works and should be released soon.
The latest iOS 4.2 beta was released more than two weeks ago, and no “beta 4” appeared on Apple’s website yesterday as many expected. With iOS 4.2 released scheduled in November and Apple apparently setting up a secret conference for developers next week, it’s likely that we’ll see a GM release of 4.2 come next Tuesday. But then again, if Apple plans to release 4.2 in late November there may be still time for a last beta and a GM release.
Once 4.2 goes public anyway, you’ll be able to jailbreak it.