The texturing and modelling all seems to be by Anthony Rivero, and there are nice looks at concept art, final skins, and various close-up views of the components of the Witch Doctor and Barbarian.
You can see all of them (in huge size/quality) in the Diablo 3 Artwork: Character gallery, or click the thumbs below. (Some of which aren’t full size since the images are so big they don’t work well in this news image viewing script.)
There are six new monster artworks in the same style as the above Character pieces. Click the thumbs to view them here, but check into the Monster Art Gallery for the giant HQ images. You see an amazing amount of detail on those; stuff you can never notice in the game where they’re smaller, moving quickly, obscured by explosions of light, etc. I had no idea Quill Rats looked that cool.