I don't know! I'm not really in a "thinking" mood right now.
Actually, if you take the mirrors and hold them apart parallel to each other, a beam of light is passing infinitely fast between them. If you slowly move the parrallell mirrors down the table, within 20 billion years or so you would have cut the table with the photon beam, like so:
m..........{llllllllllllllllllll}.........m
l l
l l
l l
l l
m= mirror
.....= light beam
I read a book about relativity that talked about this
edit: dang, my pic got screwed up. whatever, you get the idea