@Alex: Yes, that is a very good point, but it shows the challenge involved in developing non-flash based animation / interactivity without having the core 'engine' of it wrapped up in a single plugin.

It's very difficult to see how this can be easily managed, even though JavaScript is a core feature of web browsers it obviously doesn't include jQuery or the many other JS libraries that people use, so the payload of all of these JS files has got to be downloaded somehow.

I think uptake of SVG will make a big difference to the issue of file size, once we get beyond the hurdle of old versions of IE that don't support it!