I'm trying Fedora Live Workstation 21 from Gnome Test Day (build Fedora-Live-Workstation-x86_64-21-20140827.iso) and after boot, it has the same wallpaper as Fedora 20. Having different background is one of Alpha release criteria.
Proposed as a Blocker for 21-alpha by Fedora user jsedlak using the blocker tracking app because: Violates alpha criterion: "The default desktop background must be different from that of the two previous stable releases."
Default wallpaper should be set by desktop-backgrounds-gnome. Build http://koji.fedoraproject.org/koji/buildinfo?buildID=571461 as it has tag f21, I expect I managed to build it before freeze, so it should appear in next compose. If anyone knows otherwise, please let me know.
branding in kde-settings will need adjustments to use this new stuff too, I'll sort it out by this weekend
I see a new wallpaper in F21 Nightly 20140828.
Should be default now in Workstation, as Kamil verified. Closing.