Ditto on the obligatory time slider (or simple date label) critique. With out it you really have no idea what the time scale is and at some point you begin to wonder if its just looping.
Graphically, I noticed that the shadows for the dropped points seem too dark. As the map animates the high speed of animation and the darkness of the shadows make them look like dots themselves that come flying in from the East. Its a little distracting. I think there is a way to modify the shadow details in the API but not sure.
The API includes the ability to use (or not use) a shadow. I shall play with that setting and see if the visualization looks better without shadows.
Cheers!
I'll get started on that timeline! 
I took a class on dynamic mapping last year and I vaguely remember some reading on the Google Map API and the ability to control the shadow beyond just turning it off. Changing lightness and possibly extent? This may actually involve setting your own image for the shadow meaning its not the code that changes but the image it references.
Thanks!
Building upon this reply,
we are able to generate our own custom google markers using the MarkerImage variable as shown:
function addMarker() { var image = new google.maps.MarkerImage('markers/costco_image.png', new google.maps.Size(12, 12), new google.maps.Point(0,0), new google.maps.Point(6, 12)); var shadow = new google.maps.MarkerImage('markers/costco_shadow.png', new google.maps.Size(22, 12), new google.maps.Point(0,0), new google.maps.Point(6, 12)); markers.push(new google.maps.Marker({ position: locations[iterator], map: map, draggable: false, animation: google.maps.Animation.DROP, shadow: shadow, icon: image, })); iterator++; }where, var image and var shadow represent the icon and its respective shadow. The size and orientation(location?) of the icon are specified by passing the size, point, point options.
I will take a look into it further. The transparency is controlled fundamentally through the PNG image, which stores transparency in the alpha channel.
Cheers,
Edit: I removed the shadows all-together and I believe it looks better! Now to get the timeline working...
http://www.spatialan...-animation-usa/--silly browsers, might have to clear cookies before trying to watch the updated version if you don't see a change.