Looks like some Chinese manufacturers think they know what the next-generation iPad looks like -- we've seen numerous pictures today of supposed cases all with the same features: a headphone jack, a hole for a camera on the back, just one dock connector (not two), and a mysterious slit on the bottom. So, what could that be? An SD card slot seems unlikely since the cutout predominantly strips away the back of the case, not the bottom edge. Our source speculates it might be the antenna -- if all the manufacturers saw was the aluminum case design, the cutaway could've been made as a precaution, not knowing exactly what it's for. (Then again, the antenna for iPad 3G is found on the top of the device). We're thinking it might be for a revised speaker design -- the cutout is located just above and behind the location of the current iPad's speaker. Maybe we'll find out for ourselves by April, and maybe we won't -- consult your own crystal ball for that one. Some more case designs in a video after the break.