Well, a trailer and some concept art. Still, the game seems to be at a really early stage of development, which is not generally the time you announce a big book of "eye-candy by ArenaNet's award-winning artists." The whole value of a video game art book, for me at least, is that the images are enhanced by my memories of playing the game. This just seems like a bit of a tease.
With no real release date listed for the volume, who really knows? Perhaps it's just a really early tease for an art book coming in the far future? A portent of things to come? Time echoes? The mind reels.
Update: NCsoft dropped me a line to let me know that they'll have a limited number of the Guild Wars 2 art books at PAX next week, so if you are attending and are among the lucky few, all this could be yours!