Just days after General Motors decided to pull all its Facebook advertising, deeming it "ineffective," the automaker has decided it won't be advertising on the Super Bowl broadcast either. Broadcast networks, consider yourselves warned.

As The Wall Street Journal's Sharon Terlep and Suzanne Vranica report, GM's Superbowl decision is part of a larger rethink of its advertising strategy -- clearly, given this is the second time this week their marketing strategy has made the news. The fact that one of the historically largest TV advertisers in the business (and the third largest advertiser in the country) has bailed on the highest profile ad event of the year, should probably make everyone else a little nervous. GM's marketing chief said the ads were "effective' (unlike Facebook's) but not so effective that they were worth the hefty price. If you're an ad sales department and you depend on GM dollars, time to get nervous.