For example, a common approach to presenting content in an AJAXy kind of way is to just put a path after the hash. E.g.
http://www.example.com#/products/bungee-cords
It's probably really easy for the web app to figure out the right content to serve up for #/products/bungee-cords, headless browser or not.I know you'll be saying, "Of course, but apps should be doing that anyway with progressive enhancement." That's all well and good, but that leads to two separate sets of URLs: one that most users see, and one that search engines see. This fixes that.