It’s a discovery of the day: you can simply unzip an OpenOffice presentation and edit its contents. Useful if you want to gimp-edit background of a slide template:

kostja@shmita:~/1$ unzip ../1.odp 
Archive:  ../1.odp
 extracting: mimetype                
 extracting: Pictures/100000000000032000000258038F47C7.png  
 extracting: Pictures/100000000000032000000258AF6D31CF.png  
 extracting: Pictures/10000201000000580000001F5DE9F6E5.png  
 extracting: Pictures/10000000000003200000025801D1316A.png  
  inflating: content.xml             
  inflating: styles.xml              
 extracting: meta.xml                
  inflating: Thumbnails/thumbnail.png  
  inflating: Configurations2/accelerator/current.xml  
   creating: Configurations2/progressbar/
   creating: Configurations2/floater/
   creating: Configurations2/popupmenu/
   creating: Configurations2/menubar/
   creating: Configurations2/toolbar/
   creating: Configurations2/images/Bitmaps/
   creating: Configurations2/statusbar/
  inflating: settings.xml            
  inflating: META-INF/manifest.xml