Let's just say that we're looking at these images with one eyebrow raised. Not only are we entirely way too skeptical of these images for our own good, they just don't look like the iPhone HD we'd expect from Apple. Yes, the Cupertino-based company has a love affair with aluminum, but that throws up questions in of itself, considering if you actually want to make a phone call, aluminum is going to make that next to impossible (and it's not like AT&T needs any more reasons to question their network).
There's three images in total, and they showed up over at MacRumors, and they're just as skeptical as we are. They point out that within the meta data of the images, Photoshop made a quick pass through at least a couple times. And, if you look hard enough, you can indeed see that the FCC ID has been blurred. But, that could be to save someone's identity, if these are indeed the real deal.
Also, the Apple logo is awfully small, but furthermore, it doesn't look like this back cover has a smooth curve to it at all. In fact, it looks like there's actually a small flat surface right in the middle, where the outside edges actually curve upward. Almost like you could put the iPhone HD down on a table, and it'd lay flat, while the edges were lifted off. Very strange indeed. Now, if we could just see that leaked screen again, maybe matched up with this supposed back cover, we could get a better feel for what's going on here.