For Fedora 12 we have a schedule for the artwork process and tomorrow, Tue 2009-07-28, we have a milestone: Wallpaper Design for Alpha, which is important enough so I feel the need to repeat here what i wrote on the Design Team list
The deadline is supposed to be about submitting concepts, not finished images.[...]
According to the schedule, after this deadline we have one more week for some polishing (*not* final, release quality work) and packaging.
This should work as a reminder: if you work on some concepts and have not shared them with the team yet, please do it. I think this development cycle we will enforce deadlines and schedule, so if a submission comes too late, it may be too late.
In other words, we want the designs in the distro as early as possible ("release early, release often"), even if they are not very polished and want early feedback from the large community, unlike F11 when the graphics were replaced late in the process, post-beta.
The best way to submit a design is to upload it to the wiki page and write to the list.