nope...no joy with 10.6.8
in the menus, it even has "cmd-w" to close contact sheet and "shift-cmd-w" to close preview window.
aha! esc does work, but it's not the same as cmd-w (which i have been using since version 3)...it's a muscle memory thing. i'll try to start using esc from now on, but i can see it slowing me down in doing selects in large event takes due to the change until i can re-train my fingers away from the former keyboard shortcut.
(btw nice work on 500px.com, i just started following you)