With the latest update of the package ubuntu-wallpapers, the developers have finally moved on from the Hardy Heron wallpaper. Although not as innovative and elegant, it still means something, particularly the Ubuntu circles going in circles, signifying the Ibex's horns.
Here it is!: (At first it just looks like a brown square. Click on it to enlarge, and you will see!)
With GNOME 2.24 also, the wallpapers have also gotten a refresh. To keep the ISO image below 700 MB image, Ubuntu doesn't include this package by default.
Just run "sudo aptitude install gnome-backgrounds" in the Terminal, then to view the images, run "nautilus /usr/share/backgrounds" or right-click on the Desktop and click Change Desktop Background.
UPDATE: The Intrepid wallpaper has been updated to something more hot. Not the best, but better. This is getting good: (Got from Launchpad PPA testing for Intrepid artwork, not official yet)
UPDATE 2: Wow, right after I update my other post regarding the theme redesign, version 0.28.1 of the ubuntu-wallpapers package gets in. Yes, the above wallpaper is confirmed as default. But the image is changed into JPEG format.