Earlier quoted context omitted.
A while back, there was this pie-in-the-sky idea which was really interesting but not too practical, called Semantic Web. It didn't really pan out because it turns out that annotating your sites with metadata is boring and tedious and nobody really liked to do it, and anyway, search and Bayesian statistics simulated the big ideas of Semantic Web well enough for most people. The ideas behind it still stand, though, in…
Very interesting points, but there are couple of errors which undermine part of your point: 1. If the application follows the Google proposed-convention or similar, the crawler doesn't need a full-stack JS implementation; it just needs to do the (trivial) URL remapping. 2. Nothing in this hash-bang approach requires a HTML5-ready browser.
Also, how do you reassemble the hash-bang URL from HTTP Referrer header?