I haven't had to add any pictures for the PS3 but for the 360 I get them all from MS so they are uniform to begin with. Does Sony have a similar listing for each of their games?
EDIT: I went to here: http://us.playstation.com/ps3/games-and-media/
and I searched for Joe Danger and it brought me to that game's page and there is what I would call box art for it on the right hand side. They should have similar pictures for all their games.
I used a nephew's PSP and PSN account to browse their store and grab a -ton- of artwork for their PS1 and PSP Classics stuff for MobyGames (when I was still using the site) about three or four years ago. They were all in that small box format, there were no game icons or simple logos available. I think I basically used Print Screen to take shots of everything I could see. :p
So yes, I do think there's cover art for every item, unfortunately it's not easy to see online unless you have a PSN account.
The problem is not that there is not cover art, but that there is no uniform cover art for PSN items. some games use a square item, while others use the same cover that is on a UMD disc version while browsing the store on PS3 or PSP of course would show everything as a square icon. a perfect example is looking at Patapon 1, 2 , and 3 for PSP and seeing how each one has a different style cover art.
