While Twitter is a social network but wants to become your go-to messaging service, Reddit is basically the 21st century incarnation of a huge online forum - one that really seems to want to become a social network. The "front page of the internet" is adding new features left and right to help achieve that (wise?) goal. Profile pages are being revamped, for example.
And now a new partnership with Foursquare has been announced. This lets users geotag their posts with a location or a venue, thus providing more (though not necessarily useful) context for everything that goes up on Reddit.
This should already be available today. The Foursquare API is used to make the geotagging possible. It's an opt-in feature, so if you don't care for it you can just ignore it and go about your day as you normally would. As with competing social networks' tagging features, if you choose to use the functionality you'll be given a list of nearby places to pick from, and you can also search for a specific location. Redditors are being assured that neither Foursquare nor Reddit will store or share that data if you never select a location.