Spotify's surprise announcement is all about fitness and running. The company has built an all-new user experience that's designed for runners. Spotify unveiled the new feature at its event in New York City today. With the new feature, Spotify will now use your listening history and preferences to find the perfect soundtrack for your run. The app will use the hardware in smartphones (accelerometers, etc.) to determine your pace and play back songs that precisely match your performance. Here's how the company describes it:

We’ve combined the best music on the planet – recommendations based on your listening history, multiple-genre playlists and original running compositions written by some of the world’s foremost DJs and composers – all tuned to your tempo and seamlessly transitioned to ensure you’ll never miss a beat. Start running and Spotify will detect your tempo, matching the perfect music in time to your step – making you a harder, better, faster, stronger runner.

The goal is to keep your "runner's high" and motivation going through an entire workout. Spotify has gone so far as to compose its own music tracks that will keep in tune with your running pace and speed.

And later this year, Spotify will partner with both Nike and RunKeeper to bring its streaming music to both extremely popular fitness apps. The huge fitness push comes in addition to Spotify's other big changes today, which will introduce podcasts and video clips to what previously was strictly a music app. With today's event, Spotify has clearly entered a new era (and multiple businesses) that it hopes can preserve its lead as the app that smartphone users want to pay for.