Just hours after it's beta release, iPhone OS 4.0 has been jailbroken and iPhone Dev Team member MuscleNerd has the video to prove it. The method of which this was done will remain kept under lock and key until it's release this summer. Something else to keep in mind is that there is no guarantee that Apple won't throw in a monkey wrench to shake things up between now and the final build.
How many of you are already thinking about jailbreaking 4.0 when it goes live?
Video after the break!