According to very reliable informations on SonyAlphaRumors the Sony NEX cameras will not have in-body stabilization. I guess they wanted to make the camera as small as possible. They will not have built-in flash and no electronic viewfinder (only an optional optical viewfinder). Sony NEX lenses will be bigger than MicroFourThirds lenses. Even the Sony 16mm f/2.8 pancake is bigger than the Olympus 17mm f/2.8 Lens
It sounds like the real killer-feature will be the cheap price (and 1080p with the NEX5).