When placing a shadow on the wall, I attempted to treat the mirror reflection separately and darken everything within that area. I used a Soft Light PWL layer to mask the various areas for shadows, then restored incidental darkening of the trophies and chandelier with a 50% gray brush.

forum discussion: http://forums.dpreview.com/forums/read.asp?forum=1006&message=28343609&changemode=1

original image by nomad71:

nomad71's shadow: