Contradicting the suggestion of Blizz-Activision president Bobby Kotick, Blizzard says Starcraft 2 will not have in-game ads.
Kotick: "because it is a short-session experience, [StarCraft II] can actually be the model for in-game advertising and sponsorship and tournament play and ladder play for the future."
Blizzard's community manager on the US WOW forums: "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."
We'll see how it pans out!
Eurogamer: No in-game ads for StarCraft II