Sensei wrote:
Image stabilization is built into the Sony. Not the other cameras, you mentioned. All of those you have on your list are good, but for me image stabilization is a plus. I have a A350, A55o, A580. As well as a Nikon D50, D5000.. I prefer the Sony A580 for most things and bring along the A550 body and another lens for back up.
On the Nikon D3100 the image stabilization is built into the lens not the camera body. The kit lens that comes with the camera has that option so don't worry you will have that feature on the D3100................