In a more conventional usage scenario, your application is responsible for picking up updates from the changefeed.

You can see an example here of a node.js app using a changefeed to convey updates to the frontend through Socket.io: http://rethinkdb.com/blog/realtime-cluster-monitoring/

Though, of course, you can also build things other than web apps. Here's a simple IRC bot built with Go that also uses RethinkDB changefeeds: http://rethinkdb.com/blog/go-irc-bot/