Patently Apple has a few new patent illustrations from China that may hint at future iPad hardware features. The first is a second dock on the side of the tablet. As you can see above, the connector would come in handy if you wanted to view the iPad in landscape form, but didn't want to have a cable sticking out of the side. Personally, I can't really see Apple duplicating functionality in this way, though -- while a second port would be handy, it seems a waste to have a completely separate port used only half the time. Like most patents, this is only an idea at this point -- Apple isn't required to actually use it in a future release.
The second idea is more interesting, in my mind: the images show what seems to be a touch-sensitive area on the corner of the front of the iPad. PA presumes that this would be a button-less button, an area you could tap or press to do things like return to the iPad's homepage or flip pages in iBooks. Now that's a really interesting idea -- the front glass section of the iPhone and iPad is pretty much unused at this point, and if Apple could work it out so that even part of it could become functional (even in a limited way), that would be exciting.
And finally, it's worth noting that quite a few of these pictures have what's presumably a small camera sitting at the top of the iPad's screen. Yes, by now it's pretty much a given that the iPad will come with a camera in the next iteration, but there's another slice of evidence to stick in the growing proof sandwich.