General Motors (NYSE:GM) is advertising once again on Facebook (NASDAQ:FB) after an 11-month hiatus that raised questions about the value of social media advertising. Back then, General Motors had trouble seeing any meaningful correlation between social media advertising and sales results, motivating it to pull its $10 million advertising budget off the platform. At the time, Facebook had far fewer campaign measurement tools to prove the effectiveness of social media advertising. Fast-forward to today, and Facebook has better tools in place to prove its worth as a valuable medium for marketers. In this video, Motley Fool contributor Steve Heller weighs in on the development and what it means for Facebook investors.