So I gave it a try.....

xdg-open /media/mmc1/desktop.png
/usr/bin/xdg-open: line 412: xprop: not found
/usr/bin/xdg-open: line 438: sensible-browser: not found

It wouldn't install from the app manager but dpkg -i gave no complaints.

On that Maemo site, I didn't notice any dependencies for this so I'm not sure what might be wrong.