Another great take on an HTML5 flocking implementation is Alex Cruikshank's "birds on a line" demo, in which the birds also "land" on wires. I really like how Alex handles 3-dimensionality by adjusting the darkness of the birds so that the further "back" they are, the lighter they appear.

demo: http://carbonfive.github.com/html5-playground/birds-on-a-lin... source: https://github.com/acruikshank/html5-playground/blob/gh-page...