Amazing artwork-installation by Oberon Onmura, let me paste part of this description of it:
"You are looking at about a thousand 8mx8mx8m cubes, each of which is programmed to react to the density of the SL clouds directly overhead. As the cloud density over each cell increases, it simultaneously lightens its color toward white and increases its height. The result is a dynamic multidimensional map of SL's random cloud function."