Another step away from solely crowd-sourced reviews towards social circle-led content on TripAdvisor following a significant update to its Trip Friends service.
Trip Friends, which launched in June 2010 to give visitors to the ability to ask their Facebook friends about a hotel or other service featured on TripAdvisor, will now start showing links to reviews from people within their friend's network.
In other words: the friends of a user's friend.
This is probably the biggest development to the Trip Friends channel on TripAdvisor so far and plugs into where TripAdvisor is heading - tapping into the social graph of users so that they can rely on reviews from people they trust or like-minded travellers that may share similar interest by virtue of being within an existing social circle.
Adam Medros, TripAdvisor's vice president of global product, has hinted at this direction for quite some time, so with Facebook's continued extraordinary growth and with stats showing that visitors (around one in four) are starting to interact with TripAdvisor via the Facebook connection on the site, an enhancement such as this is to be expected.
Medros says:

"Travel advice from friends is incredibly useful, but your inner circle may not have all the answers on a particular hotel or destination you are researching.
"The Friend of a Friend feature increases the probability of an even greater personalised TripAdvisor experience by highlighting opinions from a larger network of travellers that know the people you trust."
So how will it work?
When searching hotels, attractions and other products on TripAdvisor, users will see reviews from friends first and then reviews from friends of friends.
The private message system included in the original integration will allow users to ask those in the network for additional information. TripAdvisor stresses that users connected to the site via Facebook will be able to toggle their security settings so that they have control over what is displayed on the site.
Driving this new development are a number of key data points, covering usage of Facebook and trust people have within a private social network such as Facebook.
The user review giant says 100 million people have now "personalised" their use of TripAdvisor by connecting via Facebook, with each user having an average of 190 friends on the social network.
It calculates the "circle" of people now available to give reviews through the additional feature is in the "tens of thousands".
Officials estimate the new service will also see an ten-fold increase in the probability of seeing personalised reviews for visitors using the site when connected via Facebook.