They look something like this, at least in the unusual circumstances of Trafalgar Square...
Once the wind picks up beyond a certain point, this one knocks a pin into the sand, and is then blown around it, gathering more energy in its bottles for when it has to move on in the last direction the wind left it pointing.
Wonderfully, the program which carries out the simulated evolution is written in nothing else but good old BASIC, a programming language I learned when I was about eight years old. Jensen is doing a lecture at the ICA next week, and I hope to come away with the source code - he says it's open source. Perhaps this will be the thing to make me go through with my project for this year, to learn a new programming language and get cracking.
Leaving, driving over Waterloo Bridge, I thought - I hope wankers don't smash them.