This was a slip up by Google and has now been taken down. Droid Life took a copy of the high-res photo for anyone interested:

http://www.droid-life.com/wp-content/uploads/2013/10/nexys-5...

And their article on the “leak”.

http://www.droid-life.com/2013/10/17/nexus-5-appears-on-goog...