Originally Posted by techie

I couldn't get any time to study the new features introduced in QBW but what you ask seems simple really
Use the code by No!No!No!Yes! for determining orientation and accordingly change the wallpaper using this command

Code:

gconftool-2 -s /apps/osso/hildon-desktop/views/<desktop-number>/bg-image -t string <path_to_image>

Modified hildon-desktop may be required though even if you use 4 screens.
Nice idea btw.Use a portrait wallpaper if in portrait orientation I might work on it tomorrow if you don't