Absolute location can be obtained through GPS navigation. Acceleration sensors and gyroscopes can be used to improve the accuracy of GPS navigation when the received satellite signals are disturbed by e.g. reflections. Also relative navigation - dead reckoning - when there is no satellite visibility, is possible.
The simplest way of using an accelerometer is to detect whether you are moving or not and thus make decisions on how location should be updated. This information can be also used in GPS system power management: power hungry GPS doesn't have to be powered on if location is not changed. More advanced approach is to estimate the distance traveled and correct possible position errors. Possible turns and relative direction changes can be estimated through information provided by gyroscope.