Used to be possible in Snow Leopard to move an app between `desktops` with a keyboard shortcut?
I figured out how to do this.  


Open System Prefs > keyboard
On Keyboard Shortcuts tab choose Mission Control
Enable the "Switch to Desktop..." shortcuts 
Now when you click on a window and perform the Switch to Desktop keyboard shortcut it'll move that window to the desktop


Guess there is a mouse component to this, so it's not pure keyboard.  But I find it way easier than dragging windows around in mission control.