This article talks about how scientists developed methods to read monitors and recreate an image of what its displaying remotely. Now if you ever wonder why your TEMPEST gear is TEMPEST'ed this is one of the reasons why.
http://www.newscientist.com/blog/technology/2007/04/seeing-through-walls.html
http://www.newscientist.com/blog/technology/2007/04/seeing-through-walls.html