The latest startup looking to bring Foursquare-style check-ins to TV viewing is Philo, which has launched its debut iPhone app.

The application lets people check-in the shows that they're currently watching, and then discuss them with friends and other viewers.

These updates can be pushed out to Twitter and Facebook too, to get friends involved.

As with Foursquare, users get badges for set achievements, such as checking-in the same TV show several times.

According to Mashable, Philo is looking to cut deals with TV firms to provide rewards and exclusive content for the people watching their shows.

The social TV space is increasingly crowded though. One of the earliest apps, Miso, has just got funding from Google Ventures.

Meanwhile, startup Starling is set to launch a similar app later this year, while Comcast is working on its own Tunerfish app.

Philo is US-only for now.