You know those online display ads that seem to know where you've shopped on the web recently? Facebook had been making the most money on them, but new forecasts suggest Google will earn the most revenue from display ads this year. What does this clash of titans mean for mere mortals? For one, Google's lead isn't just coming from tech. There are real human beings hard at work selling those ads. Google has about 2,000 people working in New York. And about half of them are marketing folks.