I've read that it is better to keep all of your JavaScript files on the bottom of the webpage. The HTML5 Boilerplate template seems to agree: http://html5boilerplate.com/
And seems to be widely used.
My question is: first, does this have any real basis? I've done testing in Firebug and it seems to have some small effect, but is it trivial? Images and other sources don't seem to start loading until CSS files and script files have loaded, but sticking them on the bottom doesn't seem to make much difference in this at all.