Kotaku noted earlier today that HD versions of several popular App Store games have started popping up in iTunes. We've since heard that it's Apple's way of distinguishing iPad games that won't run on the iPhone or iPod Touch.
So far, the games getting the HD treatment in the iTunes browser preview include Plants Vs Zombies, Flight Control, Labyrinth 2 and Worms, among others. The distinction will be important, going forward, for users to be able to tell the difference between which apps were designed specifically for the iPad and which have simply been upscaled.
It's unclear at this point if other app categories will get the HD moniker, but clearly games aren't the only genre where users that would benefit from knowing when an app was iPad-only. We'll know more as we get closer to next weekend's launch. [Kotaku]