Looks like the jailbreak app developer community can get to work on porting their apps to iPhone OS 4.0, as the current beta has already been jailbroken. However, if you aren’t a developer, don’t go trying to mess around with the redsn0w 0.9.5 beta, as this is purely a dev release. It currently only works on Mac OS X and with an iPhone 3G running iPhone 4.0 beta 1, but that’s good enough to get the devs started on getting everything up to snuff for the official release this summer.