According to the Journal, GM still plans to use Facebook as an advertising platform--it will promote its products on Facebook, and continue to build social rapport with its customers via Facebook--it just won't utilize Facebook's paid ads feature. If other Facebook advertisers are paying attention to GM's actions then this could be an issue for social network, which relies almost entirely on advertising sales to turn a profit.

Of course, the WSJ notes that GM only spent about $10 million last year on Facebook ads, which is a tiny fraction of GM's total U.S. ad spending ($1.8 billion), and a tiny fraction of Facebook's total 2011 revenue ($3.7 billion). So GM's pulling out may not affect Facebook's bottom line directly, but it does raise the question--is Facebook advertising worth it?

GM Isn't Alone

Not…really, according to a , a provider of search engine marketing software and services. WordStream has released new research that compares the value of Facebook's ads to Google's Display Network, which is the part of Google that lets companies place ads on Google's related sites, such as YouTube and Gmail.

According to , while both Facebook and Google have huge "potential reach," the average click-through rate on Google's ads is 10 times the average click-through rate on Facebook's ads. In other words, Google's ads are essentially 10 times more effective than Facebook's ads are at getting people to, well, click.