The Zune was officially released today, so I headed on down to EB Games to pick up my pre-ordered device (black... not brown... I guess I'm not cool enough for brown) and the first thing I did was sync over this Zune background image that Adam made for me. It isn't a perfect image, after he made it we figured out that the ideal background image would be 320x320 and arranged to look good cropped for the device (240x320) or for the TV output (320x240).
This background looks great for the vast majority of my usage (my Zune is usually not hooked up to a TV) though, so I thought you might like it as well. Go ahead, download it to your My Pictures folder... your Zune software will pick it up and you can sync it over to use as a background.