Gyro Sensor? This does make sense. Apple already added a gyroscope sensor to the iPod Touch. This is used by games to better let them measure their movement in space.
Camera? This prediction seems like a given at this point. We have seen cases with cutouts for a front-facing camera. A front-facing camera would be used with FaceTime and PhotoBooth. A camera on the back makes less sense for a tablet device. Can you imagine holding your iPad up to record some video or take a picture? If you had a video camera on the iPad it would follow that they would also bring iMovie to the iPad.
USB Port? There are things that makes this rumor credible. The first one is the new EU requirement that all cell phones sold in Europe support charging via micro-usb. While the iPad is not a cell phone it would be in Apple best interested to standardize across their iOS platform.
SD Card slot? The second reason for a USB port is to replace the current camera kit. This would go hand in and with the rumor. Currently you can connect either a USB cable or a SD Card if you have the connection kit. Functionality is limited. You can use it to upload pictures and plug in a keyboard but not much else.
Other nice improvements would be a thinner, lighter form factor and a better battery. We will see in February.