Facebook has teamed up with travel website TripAdvisor to let users get advice and reviews from friends when planning trips. Once a user is logged into Facebook, the TripAdvisor site shows a list of Facebook friends, along with the places they’ve visited.

TripAdvisor’s new Facebook integration makes it easy to find friends’ reviews and learn from their experiences in the same locale. Zoom into any area of the map on TripAdvisor, and pushpins show you where your FacebookFacebook pals (who’ve used the “Where I’ve Been Facebook” app) have traveled. It’s a simple matter to click on one of those pushpins and see friends’ reviews of that destination.

It’s not surprising that TripAdvisor would team up with Facebook in this way, given that the company bought the “Where I’ve Been” Facebook app in 2007 for $3 million. It seemed like a high price at the time, but maybe now that investment is coming into fruition.

TripAdvisor was already the world’s largest travel site according to comScore, and now with Facebook integration, users will find it even more useful, discovering if those restaurants and hotels are actually worth visiting. We like the way this new app makes it easy to find reviews and comments from trusted friends.