The new Symbols function and Heatmap Layer in the Google Maps API mean that it is now much easier for developers to create compelling map visualisations.
Both these features make it much easier for developers to add animations to maps. The result is that Google Maps can now beautifully render data both spatially and temporally.
This morning I've been playing with the new Heatmap Layer. The Blitz Map is an animated heat map of the bombs dropped on London on the first night of the London Blitz in the Second World War.
I've cheated a little with the timing on the map. At the moment the map just adds the bombs sequentially, step by step, and doesn't use a real time-frame. It should be simple however to add a real time-line to the map at a later date.