You've all got one...............!
The adapter for the new Nikon V1 will allow Auto Focus with Nikon AFS lenses. This is not digiscoping but you are getting into digiscoping territory with a 300/4 plus 1.4x = 1134 mms.
Once you've used an Electronic Viewfinder you can't go back. The ones on the Fuji X100 and Nikon V1 are excellent.
Thanks Neil - I was thinking specific to the NEX5 (or NEX5N). The viewfinder would be a good addition to digiscoping then?