It's coming, the same way the Cubs are allowing advertising on the outfield walls this year for the first time. Well, for the first time in a while, right? I'm sure those walls had ads in the halcyon days of yore, just like Fenway did and does. Well, at least not since 1937, when the ivy was planted, according to Chicagosports.com. I haven't been able to find out definitively either way about prior to that, but I can find no information indicating that there was advertising, so, we'll go with there's never been ads, until shown otherwise.
According to the book "Ballparks Then and Now" by Eric Enders: The stadium remains a hold-out in another area, too. It is the only current major league park with no display advertising, a classy feature that makes it easier for fans to concentrate on the game at hand. An accompanying photo, pre-ivy, supports that point. It shows a bare left field wall, and centerfield stands that come right down to the playing surface. Another interesting point in the book is that Wrigley was one of the first parks to have lights -- they were installed in 1915 for "a nightly postgame hippodrome show." It goes on to say that in 1941 the owner Wrigley had lights in hand for baseball purposes, waiting to be installed, when WWII broke out, and he decided to donate the steel to the war effort.
Now it's the "Taco Bell Grande-Sized Double Chalupa Meal Fiesta Bowl Brought to you by Ford Motors and Verizon Wireless". Suddenly, I'm hungry. But do you hit the drive thru, or call... That is a pretty nice pic too. I bet it'll look the same if they move HQ to Trindad and/or/if Tobago.