I hereby coin the term "voroboid"! The small dots are "boids" that fly in flocks, and they are overlaid with a voronoi diagram with cells coloured by area size.
I took Mike Bostock's Voronoi Diagram example and combined it with a great boids flocking tutorial by Harry Brundage. Thanks to Mike for colouring the voronoi cells by area.
Move the mouse and you can affect the boids' movement.
You can read more about boids on the Wikipedia page.
This demo requires a modern browser with SVG capabilities.
See also: Bubble Harp by Scott Snibbe.