To the three :-) people in the world who care about blinking lights on a CloudMade Map : Evidently CloudMade and the web browsers can't handle  large amount of overlays i.e. 1000s of them :-). So the solution is to map.removeOverlay() before map.addOverlay(). If you don't remove the overlay before you addOverlay() then the browser slows down and leaks a large amount of memory.

I'll post a video later of the incredible Das Blinkenlights :-) but you can try it yourself. Just click on one of the following URLs to try it yourself (the map will be all black until somebody uploads some geotagged photos which could be anywhere from 1 second from now until an hour from now):