In the months leading up to Facebook's initial public offering this past summer, the company admitted in a filing with the SEC that the fast-moving shift from traditional desktop or laptop computers to mobile devices was hurting the company's advertising plan.

Facebook also listed mobile among the company's "risk factors."

"The results today are really underlining how important mobile is for Google going forward, as consumers move away from the PC to phones and tablets to do what they do," said Carolina Milanesi, an analyst with Gartner Inc. "Consumers spend less time on the Internet and more time on their apps, and that plays a role in how we use search and the role that search plays in our lives."

Much will depend on the role Motorola plays in Google's mobile strategy, especially when it comes to search.

"I think this is not something you fix in a quarter," said Milanesi. "It's such a change in the market with the role that search has. Google is soul searching how they're going to monetize in this next phase. How will consumers search? How do they go about serving that need? There's a big opportunity there."