Mobile searches are overtaking PC searches around the world, and therein lies the opportunity for Google to sell and place new ads specifically designed for mobile searches. Bringing ads to mobile devices isn't just a matter of scaling down current ads. There just isn't enough screen space for lengthy keyword-based ads. Google also knows that when it comes to mobile devices, users prefer search from specialized apps like Yelp or Amazon instead using their browsers. So, Google's mobile ads will be more pictorial to simulate the feeling of app-based searches.