(Note: this is a pretty technical post.) The iPhone's passcode is pretty superficial. Only the UI code actually enforces it, and this is one of the results of

(Note: this is a pretty technical post.) The iPhone's passcode is pretty superficial. Only the UI code actually enforces it, and this is one of the results of that distinction. In fact, when you unlock, you are still viewing the same process as you were before it was unlocked. It just called the "_unlockWithSound" method and set an internal state to unlocked. Edit: as pointed out to me on IRC by comex (author of JailbreakMe), there is lower level protection in the "lockdownd" service, but since the UI controls that, it doesn't really provide any additional security except it blocks iTunes syncing and such). However, with this "hack", you are still locked, so you can't do anything like opening apps (again, the UI process locks opening apps, as part of their "security"). But, I did some experimentation, and here's what I found for impact: - You can read and edit contacts, of course. - I am not sure if phone calls work, but they didn't appear to. - While clicking an email address does nothing, clicking the "send contact" lets you send an email to whoever you want, custom address and all. - You can view all the photos by pressing the "add photo" on a contact you edit. You can also take new ones saved to there. - You can send SMS and MMS using the same method as for email, but selecting MMS. - You /cannot/ enter Safari or go to the homescreen: unless someone finds another similar "hack" to exit the app, as then you could see the icons (but, as the "is locked" flag is still "true", it won't let you launch apps). - FaceTime doesn't seem possible. This is a serious issue, and with the publicity it already has, I would only expect Apple to fix it (with a 4.1.1 firmware release, of course, I don't expect them to care about their iPhone 2G owners back on 3.1.3) within two weeks. However, if they want to fix this, they need to redesign the workings of the lock screen. The current way it works is incredibly simple to circumvent. Finally, on an unrelated note, the same exploits used in the jailbreak tools like "greenpois0n" and "PwnageTool" can be used to get around the passcode and get full filesystem access, or just remove it altogether. But you do need a computer for that, which you don't with this.