The Ghosting Editor lets you create images that echo the animation, letting you visualize movement and position of animated objects over time.
Character courtesy Create 3D Characters
Previously in Maya, when you had multiple meshes selected and you wanted to change the way ghosts appeared in the scene, you had to edit each meshes' individual attributes in the Attribute Editor; there was no way you could apply sweeping changes to all ghosts in the scene.
Now, the new Ghosting Editor gives you an interface where you can easily modify Ghost attributes one by one, or as a group. Unlike a Motion Trail, which represents keys around your animated model, an Animation Ghost shows you the object rather than a trail, allowing you to make better decisions about the animation.