This morning, Foursquare made a subtle but significant change to each and every venue page that could have major implications for business owners: the addition of Facebook "Like" buttons.

Now Foursquare users can browse venues, "Like" them and instantly share that activity back with their Facebook friends.

Users' liked venues will not only be shared on Facebook in the activity feed and visible on Foursquare, but will also become a part of their Facebook profiles. It's more free promotion that could help the most "Liked" venues attract significant offline foot traffic.

For users, the Like buttons also offer an immediate way to see which Facebook friends give a thumbs up to restaurants, coffee shops, bars and city attractions without having to dive into the venue tips.

Foursquare's Head of Product, Alex Rainert, tells us that this is just the beginning and the company will monitor user adoption of the "Like" buttons to understand how best to further enhance Foursquare's Facebook integration.

He says that Foursquare is primarily "thinking about other ways to leverage some of the new Facebook stuff in a way that isn't just this low hanging fruit functionality... we wanted to get this going to start seeing how people use it."

Foursquare joins more than 50,000 other websites that have integrated Facebook's new social plugins since they were announced last month. Check it out for yourself and let us know what you think in the comments.

[hat tip: Vadim Lavrusik]

[img credit: Aidan Jones]