I don't find this one as informative as similar visualizations I've seen in the past. I think because the files fade out if they haven't been edited in a while you can't really see the progress of the project itself.
I think they found a fair balance between informative and appealing. I mean, if every single one of those textures stayed on there the whole time I don't think it would have looked anywhere near as nice.
EDIT: I assume it was http://code.google.com/p/codeswarm/