F17 Beta Wallpaper touchups

[Máirín Duffy]

Hi Alexander,

(I'm cc'ing the design team for reference)

I think so far the F17 wallpaper has been a real hit. We've gotten a lot
of positive comments about it. Thank you so much for doing such a great
job on it.

Matthew Garrett is doing Macbook Air testing of Fedora 17, and he
noticed even though the wallpaper looks great (maybe just a tiny bit of
banding) on most computers, on the Macbook Air it shows strange
stairstep banding. I took a photo of it here:

http://www.flickr.com/photos/mairin/7090541057/

I'm going to try to adjust the image a bit to try to eliminate this
artifact and to dither the banding so the image appears a bit smoother.
Do you have any ideas / suggestions for updating the wallpaper further
for final? I was thinking about playing around with some of the
fireworks effects since I'm going to be poking at it anyway. Let me know
what you think. I'll follow up with a post of what I come up with. 

~m