This is something I've been mulling over for a while, and someone has asked for more details. So here it is, a quick and dirty blog post.
Below shows a standard wiring layout for a single switch and bulb, as you can see there's no neutral in the switch, only live in and switched live out.
|The Problem (Click to expand)
So, can we get a neutral to the switch without tearing the walls apart? Kind of!
I am not an electrician. This may not meet building or safety regulations. This is untested! Do so at your own risk! Electrical work should be carried out by a qualified electrician! ETC