Verbolten's theming is being done by a company known as Adirondack Studios. Who are they? Well, they're the company responsible for the theming in Busch Gardens Tampa's Jungala, Universal Studios Islands of Adventure's Dueling Dragons, and Universal Studios Orlando's Woody Woodpecker's Nuthouse Coaster, The Simpson's Ride, and the world famous indoor launch coaster, Revenge of the Mummy.
Let me just run that by you again. Williamsburg, Virginia is getting a multi-launch coaster themed by the same people who themed Revenge of the Mummy at Universal Studios Orlando. I guess you have to put that $54 million into something.
Also, ivy, lots and lots of ivy.
EDIT: As Newsie pointed out they're also working with ThemeWorks who has did a lot of the theming for SeaWorld Orlando's and SeaWorld San Antonio's Journey to Atlantis rides, as well as the beautiful Treasures of Poseidon building at Universal Studios Islands of Adventure.