Since the iPhone 5 finally landed in the hands of excited customers on Friday there have been numerous reports of a "rattle" or 'thud" coming from inside new phones. What is the weird sound in these online videos?

According to Apple forum discussions and reports from tipsters, it appears that the sound is being caused by a loose battery. In one case, a user simply took her phone to the Apple Store, where a Genius reapplied adhesive to the battery and sent her away. Has anyone else experienced this problem? How many supposedly new phones are affected?

It's important to remember that Apple is literally pushing out millions upon millions of iPhones, and that even with strict manufacturing tolerances, you can't expect every single unit to ship perfectly. That said, we'd love to get to the bottom of this issue, so send us any information or videos you have, and we'll update as we get more information. [Thanks Trevor!]

Update:

The first video posted has been marked as private. We're trying to find out why. In the mean time, we've posted another video.