Looking pretty good. The only comments I would have is around the use of the <noscript> section.
You're using the <div id="main"> in there as well as outside of that section. Technically, since both could be rendered at the same time. Though programmatically, the div in the <noscript> section is not targetable, at least not in Chrome which I just quickly tested in (And of course if they are both being rendered, JS is disabled anyway :p)
The other question I would pose is the necessity of the <noscript> section. If you're progressively enhancing (like you are doing currently), then you'll probably find that it's not really necessary to have a <noscript> section.