Hm. It looks like Ubisoft hosted 2GB of concept art for unannounced games on their server. And Neo-GAF found it! But then Ubisoft pulled it. Some people have rehosted some of the stuff, and I’ll post it.
Prince of Persia
Splinter Cell 4
Splinter Cell 5
Star Wars PSP
Shaun White (Snowboarding game)
EDIT: My image links didn’t last as long as I wished them to. If you want the media, your best bet is to check the Neo-GAF thread where posters have been rehosting the images.