"Bobby Kotick, chairman and CEO of Activision, soon to be Activision Blizzard, recently said that the company will be trying to maximize revenues out of the highly anticipated StarCraft II. To do this, Kotick asserts a new business model for the franchise, which could potentially include in-game advertising."

http://pc.ign.com/articles/857/857150p1.html

To remind everyone, Blizzard previously denounced any changes as a result of the merger:

"This will not impact Blizzard’s games."
"There will be no changes in the way Blizzard operates."
"[B]oth of our companies will continue to operate as they have previously with regard to game development."
"the transaction will not have any impact on our games"

Activision Blizzard FAQ

Is World of Warcraft next?

We have no plans to have in-game advertising in StarCraft II. We believe Bobby was actually referring to Battle.net, which has always included ads.