I love those glass blocks. Where did you get them?
Here's the url that prompted my original question:http://www.philcooper.com/gallery/loh-00/second_view_of_private_bath_lots_of_mirrors
The 12"x12" mirrors in this bathroom appear to be real glass, since the edges are beveled, and I've never seen beveled plastic mirrors.
What is the mastic people are talking about in this thread? If it never hardens, that would suggest even if the mirror cracks that no big chunks are going to fall off the wall and slice you open.