Sure, the Science Museum of Minnesota has always used the side of its building to advertise. To advertise its own shows, that is. But this is the first time they've used the space to advertise someone else's product. (Yeah, they like to stretch out the change, so there are a few days of confusion as the poster gradually changes from one to another.)
Here's a closer view.
[UPDATE: I guess there's a reason they haven't done this in the past. It's a violation of St. Paul's signage code. The sign was for the benefit of the Rebublican Convention. The Science Museum is saying they thought the Republican National Committee was responsible for getting the proper permits. The ad will be taken down on Monday -- three days after the convention ended.]