Newton, Mass.-based TripAdvisor just announced it has acquired Palo Alto-based EveryTrail. The acquisition expands TripAdvisor’s mobile offering and puts a strong emphasis on mobile traveling options. EveryTrail has developed a GPS-enabled publishing platform to create outdoor tours and city guides for mobile devices. The combined technology will give users mobile access to TripAdvisor’s millions of travel reviews and opinions. The terms of the deal were not disclosed.

“Every day, more people are opting to use mobile apps as a way of consuming travel information,” said Adam Medros, vice president of global product for TripAdvisor. “EveryTrail bolsters our continued commitment to grow TripAdvisor’s mobile offering, and enable travelers to access walking tours, city guides and hiking trails directly from their smartphones.”

This is TripAdvisor’s second big move in just over a month. Towards the end of December TripAdvisor launched Facebook integration to make booking travel plans social. Given Facebook’s strong mobile push in 2011, I would expect to see similar integration with their mobile devices.

“Like TripAdvisor, EveryTrail is possible because of a global community of travelers who share their stories every day,” said Joost Schreve, CEO of EveryTrail.  “The mobile platform that we provide lets travelers turn these stories into highly engaging mobile travel guides that help other travelers enjoy their trips even more. We are delighted to join TripAdvisor in this exciting new phase that will give us the ability to bring our tours and guides to TripAdvisor’s 40 million travelers all over the world.”

TripAdvisor launched it’s mobile website in March of 2010 and has since added apps for the iPhone, iPad, Android, Nokia, and Palm smartphones.