The Star Wars Art: Visions book just came out and is available from amazon. I was pretty surprised when I saw they used the sketch for my painting "Yobana" on the title page. The book was written by Lucasbooks executive editor Jonathan Rinzler and George Lucas and includes paintings by artists who don't normally paint SciFi subjects. Artist like Jamie Wyeth, Michael Grimaldi, Will Wilson, Daniel Greene are some of the guys who did work for the project.
Heres a mini documentary about the project on youtube