EDIT: 20th June 2009. It would appear this billboard is not as it first appears. A number of you have pointed out that it looks Photoshopped. I will not be removing this post in the interest of clarity, but I would like to make it clear that, upon further examination, I no longer personally believe it to be part of a genuine ad campaign, from the people who brought us the creation science museum. Please read comments for more.
Update: Andrew McKenzie, from answersingenesis, has verified that this is indeed a Photoshopped picture, in a detailed comment below.