The wallpaper competition for sidux' second release has been running for several weeks now and has received several strong entries already.
You can see all the current submissions here along with the competition guidelines and conditions—if you're short on creative juice, then check out the various resources in the Artwork forums for GPL'ed components, links to tools and guides, or simply to ask for help on getting started.
The winning artwork will also serve as the source of inspiration for other component artwork such as the kdm login and ksplash theme.
The final date for submission is the 31st March, with the winner announced on the 2nd April—so get those entries in quickly!