Sony applied for a patent for a translucent mirror in a camera without a viewfinder. According to the patent's summary, the composition will be done through the LCD display:
"In recent single-lens reflex digital cameras, a display such as a liquid crystal display (LCD) panel is disposed on the back of a camera body such that an image inputted to an image pickup device can be viewed using the display. For example, there has been proposed a single-lens reflex digital camera, having no optical viewfinder, that allows a user to take photographs while the user checks an image using a display disposed on the back of a camera body."
Removing the EVF will reduce the size, weight and price of the camera. This is the current Sony implementation of the translucent mirror (Sony a33 and a55 models) with an electronic viewfinder:
