In this deep dive, Sean McKenna from Windows Phone and Greg Hodgal discuss how to program for Windows Phone 7 using the accelerometer.  An accelerometer is a sensor that measures acceleration forces such as gravity or the forces caused by moving the sensor. All Windows Phones have at least one accelerometer sensor that, when accessed by the managed Accelerometer API, can be used to provide input to Windows Phone applications including both Silverlight for Windows Phone and XNA for Windows Phone applications.