R.OG, a MacRumors forum member, posted his teardown of the new desktop earlier today. He took the iMac apart to replace the 3.5-inch drive with a SSD and found the logic board only has one normal sata data connector and a custom power connector.
R.OG also noted that the stand is mounted from the inside so VESA mounts will be a problem with the new device.
Taking the teardown further, R.OG also removed the CPU to install a i7-3770 processor. Check out some photos below or hit the link for more.