Sorry, the other answer is wrong. The current e-mount lenses will work on this camera, however they will be in crop mode. This means the camera will detect that it is not a full frame lens and only use part of the sensor. In reverse, the full frame lenses will work on the current NEX line up. In that situation it will just waste the capability of the lens.
Yes, it has been done. See the Steve Huff photography website. Steve's site is heavily attended by Leica folks. Steve says that, with those lenses, he gets better results with the A7 and A7R than he gets with a Leica M9! Of course the A7 and A7R are not as compact. The website will probably tell you where to find an adaptor. If not, you could contact Steve through the site.
i'm not sure i can "justify" getting this camera.. but i can give you my experience with it.. and my opinion of it..
I have been an avid DSLR user for about 6 yrs.. i'm still an amateur but feel very comfortable shooting. It is a very different experience than shooting any modern DSLR. Image quality wise, it is noticably sharper and clearer than my canon 5dmk3 even using the same lens (with the metabones adapter)
i have the 55mm f1.8 sony lens. it focuses faster and is truly a stunningly sharp lens. With an adapter it takes about 2 seconds to lock on a good focus. which is fine for portraits or landscapes.. but i wouldnt expect to use this camera for action shots unless you can prefocus.
the interface is rough around the edges.. i've disabled the wheel on the back of the camera because its too sensitive and way too easy to bump or move on accident. if you are an HDR shooter.. this cameras HDR features are very limited.
Focus is fast enough.. but modern DSLRs are MUCH faster to focus.
battery life is terrible.. you'll get about 300 shots out of a battery before you need a recharge.
for me.. this camera is much more like a film camera.. i really slow down.. think about the shot i want to take.. double check all the settings then take the shot.. if everything is right.. you'll get a truly stunning and sharp shot.. if you didnt have the settings right.. you'll know it.
this is not a camera where you can just hold down the shutter and think "well i'll get one or two good shots in focus.." , the "spray and pray" approach doesnt work with this camera.