One of the features of mirror-less cameras is the small distance between the lens mount flange and the sensor. That small flange to sensor distance opens up the possibility to use adaptors to mount older manual lens on the camera. If you can afford them, you can mount Leica M-mount lenses on a NEX, these lenses have the advantage of being designed for a mirror-less film camera which itself had a short mount to film distance. I don't have that kind of money to spend at the moment!
More on the NEX 6 and manual lenses martin Sun, 07/21/2013 - 09:36
When using Sony lenses in manual focus (or DMF mode) the camera can be set to zoom in when the focus ring is turned. This works because the E-mount lenses use fly-by-wire focus so the camera knows that the focus ring has been turned.