I've read all over the place that it can't, it's not supported, etc... And then all of a sudden, mine did it, was 'stuck' like that for about 5 minutes, and went back to normal when I hit the menu button. at first I thought I was imagining things, so I actually called my wife into the room to see it with her own eyes.
No idea what happened to it to make it happen though... I had opened Netflix, then hit the home button while bobbling the phone in my hand. It went to the home screen, and even flipped vertically several times back and forth. The 'bottom' row of home page icons stayed at that end of the phone, and the search bar stayed at the 'top' of the phone, but the apps on the home screens were turned together 90 degrees, and scrolled from side to side (or technically top to bottom... A side swipe from the charger to the earpiece moved the screen... Make sense?)
Best I can come up with is that Netflix hung up a process and held the screen like that for some odd reason... I have not been able to replicate the situation, so I'm assuming it was a glitch. A cool glitch IMHO, but a glitch none the less...