Funny, I had a friend who wanted to do something similar for festivals, he never will though, just musings!
It looks awesome though. The picture of the latte art and the naked portafilters really scream quality to the coffee professionals like me. And also you are ethical, but not fairtrade, appealing to regular people, and its in a VW bus.
I know several people who do the festival circuit with good-class coffee, and many seem to get a great deal of fun from it. And it certainly evens up the number of really awful coffee stalls you get at these places. Have you seen Colonel Grumpy's genuine Guatemalan coffee bus?