Hashbang URLs are bad because they damage the addressability of the Web. If I can't take a URL, telnet to port 80, run GET /path and get back a representation of the thing that the URL points to, that URL isn't really part of the Web - it's part of a JavaScript application delivery engine that happens to run over HTTP.
I don't think anybody opposes it in cases where it actually makes sense, but I assert that the dividing line is pretty clear.
How would you categorise Flickr, or YouTube, or Wikipedia, or Yelp, or Lanyrd, or Craigslist - or pretty much any other UGC site? I'd argue that all of them could be described as both.
Flickr's photo indexes and Yelp's listings and reviews should probably be accessible via regular old URLs. But Flickr's uploader screen? Adding a new listing to Yelp? If you're ok with leaving behind users who have javascript turned off, it simply _does_ _not_ matter. In those cases, why not take advantage of the snappy UX that shebanged interfaces offer?
Personally I'm not OK leaving behind non-JS users in my own development, but provided a site's public pages are accessible I'm not too bothered what they're doing when people log in.
Which command line option on curl does that? (Maybe they haven't updated the man page? http://curl.haxx.se/docs/manpage.html ).
Oh, if you reply, could you do it in the form of interpretative dance.
Yeah, not that hard dude.
So easy, you've actually got it wrong.
Certain special characters after the hash-bang need to be url-encoded, and then that value needs to be added to what's before the #! by including a query string parameter of _escaped_fragment_, checking first whether there is already a query string so as to append the information rather than incorrectly whacking on a '?'.
Plus, this isn't in the form of interpretive dance. So no content for you.