Today Gruber observed from a New York Times article about Google's second quarter earnings that mobile ads aren't worth as much. It's no surprise that mobile ads don't bring in as much traffic as desktop ads. Think about where you are when you use your mobile phone. You may be at home watching television, you may be walking down the street, you may be at a stop light trying to lookup directions, you may be out at a restaurant. As Luke Wroblewski says in his book Mobile First, people are using their phones with one eyeball and one thumb. Mobile usage happens on the go, for specific purposes. People often don't give the device their full attention, it comes in sporadic bursts. No wonder people on mobile devices are less likely to take virtual detours to click on ads.