With the 4th generation iPhone HD/iPhone 4G almost certainly ramping up for production in anticipation for a WWDC 2010 introduction, it's not too surprising parts like the casing are beginning to show up in the wild.
What SmartPhone Medic is showing in the video below matches up to the iPhone prototype Gizmodo got their hands on, once again adding weight to the assertions that this is pretty close to the final design we'll see this June.
SmartPhone Medic also had the iPhone G4 screen back at the end of March. Impossible to keep these things secret anymore?
[SmartPhone Medic, thanks Tim for the tip!]