NBC, currently majority-owned by General Electric
Pulling out because Google underperformed under these conditions doesn't seem entirely fair, but the AdWords system was always sort of alien to the entrenched buyers and sellers of media space. Pulling off an instant revolution worked online, where Google owned the biggest, baddest search engine and could set its own rules. It's harder to tell NBC, Walt Disney
Rumor has it that many of the remaining Google partners are thinking about jumping ship as well, and I wouldn't be surprised to see Tennis Channel, Bloomberg TV, Ovation, and others doing exactly that. Mark down this first iteration of AdWords-driven TV advertising as an abject failure -- but don't forget that Google is sticking a more direct finger in the marketing pie with the Android-powered Google TV platform.