I'm running emacs 23 cvs binary on Snow Leopard. I found that the background color of my selection region won't follow settings of my color-theme, the following line in color-theme-install doesn't work as designed:

(region ((t (:background "#2e3436"))))

To work around this, you need to set the color of region background manually:

(require 'color-theme)
(require 'color-theme-subdued)
(eval-after-load "color-theme"
  '(progn
     (color-theme-initialize)
     (color-theme-subdued)))

(set-face-background 'region "#2e3436")