We at the Fedora Design Team are not arrogant enough to think the default wallpaper we provide is the ultimate choice for everyone, we understand the diversity of our users and their tastes and trying to make a larger audience happy we want to provide a set of alternatives. The idea is not new, we started playing with it a couple of years ago, but only now it came to fruition.
Of course, other distros are doing it too and they may arrived faster to results, but we used the "Fedora way", more Free and more Open :D It started with a wiki page collecting submissions from everyone, it was announced on blogs/Planet, Fedora Weekly News, microblogging and so (as a writer for FWN I made sure the happenings are documented as they go).
After a generous submission interval we had the members of the team expressing their option/preferences/votes (you want the selection made by someone with an understanding about design, usability, photography and such) and this ended in a "winners" page containing the most voted images, some of the submission are creation of Fedora contributors and some are Free images gathered from the internet (Flickr)
The current step is to double-check the licenses (we became quite paranoid about this after the InvinXible/Solar incident) and at the first pass we struck down a couple of them due to restrictive license (CC-BY-ND and CC-BY-NC are not Free, so not acceptable for inclusion on Fedora). The second pass is to contact the unknown photographers and learn if they are happy with the attribution we are able to provide, some already replied positively. Expect the package to hit the repos before the Beta release and get a few improvements until final.
One of the last steps we are still trying to figure is providing attribution (author name, license and URL) in the wallpaper chooser application as tooltip, the current idea is to (ab)use ane XML file in /usr/share/gnome-background-properties/) and another is to try to persuade some spin maintainers into liking and using the package (it will probably be at least part of the Design Suite).