It’s a canvas tag version of everyone’s favourite old-school demo effect. It obviously requires the canvas tag, so anyone out there still persisting with IE, perhaps quixotically hoping that it will one day turn into a web browser, won’t be able to see it. It works very well in Safari (in OSX, at least), and Firefox does a reasonable job of it. Strangely, it’s faster in Safari on my hackintoshed netbook than it is on my 2.4GHz Thinkpad in Firefox.
The canvas tag code is a port of the latest Woopsi example - a fire demo that uses the SuperBitmap for output.