These seem like the best community wallpapers so far and I'm really glad they've finally decided to include some non-photos as wallpapers (we've had enough flowers in 10.10).
The default Ubuntu 11.04 wallpaper has been slightly modified:
I have made subtle changes and introduced new light refractions. We can continue to add light streams and re-balance with each release - the landscape becomes gently lighter and brighter and gains in complexity to reflect our drive towards 12.04 :)
IMHO as we move towards becoming more of a 'household' platform and with the great changes coming with Unity (launcher/dash) general users will get reassurance from the familiarity of the wallpaper and will also identify with it as part of our personality in new screenshots.
-via LP
Download all the Ubuntu 11.04 community wallpapers from HERE (I didn't link to the .deb because it would replace your current community wallpapers package).