Yes it calculates the distance to the object for each frame and moves towards the object in smaller and smaller steps, making a easing effect.

You can also have it like....

onClipEvent(enterFrame){
speed=7;
this._x+=(_root.xpos-this._x)/speed;
}


The xpos variable determines the position where the movieclip will go. For a initial position set the xpos to the proper value in the first frame of the movie.