Hi,

For F17 we had no supplemental wallpapers, because noone wrangled them. I will do that for F18 and will announce it on monday.

https://fedoraproject.org/wiki/F18_Artwork/Submissions/Supplemental_Wallpapers

According to the schedule from Jaroslav

http://jreznik.fedorapeople.org/schedules/f-18/f-18-design-tasks.html

the submission period should be already started and end on 30th of August. But I think its also doable until 5th of September, I have spoken with Jaroslav about that.
I have also spoken with Martin, he will package the wallpapers when we have them selected.

br gnokii