Havin' an iso image of the latest movie on dvd is all pretty well, but you still would like to see it. You could mount the image and let xine play the vob files or take advantage of the dvd:// capability of xine like this:

xine “dvd://path/to/your/file.iso”

Even handier would be to have that command in your context popup (by right-click'ing the file). To have that in KDE, open up the directory "~/.kde/share/apps/konqueror/servicemenus/" and make a xine_iso.desktop file with the following content. 

[Desktop Entry] ServiceTypes=application/x-iso
Actions=Xine ISO
[Desktop Action Xine ISO]
Encoding=UTF-8
Exec=xine &qout;dvd://%U&qout; Icon=exec MimeType=application/x-iso
Name=Play DVD ISO with xine

Now right-click an iso image file and look under "Actions"

Enjoy the movie!

More help on editing context menu's can be found at: http://legroom.net/2007/04/20/adding-custom-actions-kde-context-menus