If you are using a Lumia 630, 635, 930, or 1520, you may want to check the Store for an update to Motion Data. Version 184.108.40.206 is now live in the Store, although like many of the system apps for Lumia phones, this one forgoes a formal changelog.
What is Motion Data? Motion Data is a special feature originally built by Nokia for their Lumia phones, based off their beta Motion Monitor app from late 2013. The system app uses GPS and the accelerometer, letting the phone collect your steps and location for use in third-party apps like Bing Health + Fitness through the SensorCore API.
Only phones with the newer Snapdragon 400, 600 or 800 series can leverage SensorCore, as it uses aspects of the chipset not found on earlier S4 hardware. You also need the Lumia Cyan firmware to enable.
Today's update likely brings some fixes and optimizations, so if you use Motion Data (it is opt-in), you should grab the refreshed version.
How many of you are using Motion Data daily? Do you find it useful?