The “ubuntu-wallpapers” package has just been updated in Ubuntu 11.04 Natty Narwhal. There are seventeen new wallpapers in total. A new default wallpaper has been added too, as you can see from the Screeenshot bellow (the last one), there is no special difference between Ubunu 10.10 and 11.04 default Wallpaper.
In order of appearance, their names are: Arboreal ballet, Aubergine Sea, Berries, Bird, Fabric, Green, Grey day, Holes, Ilunabarra Azkainetik, La no alto, Quandro, Signpost, Tiny Worlds, Touch the light, Tri Narwhal, Variations On Natty Narwhal and White flowers. These wallpapers are extremely beautiful all in high resolution.
The ubuntu-wallpapers Package that contains all the wallpapers can be downloaded from this link. [3M]