* Ajax responses are often JSON content. How do I apply a CSS/XPath selector on it?
* I guess #! URLs could be transformed into _escaped_fragment_ URLs [1]
* I know twitter has an API. It was just an example. Maybe this example [2] would be more relevant (content could also be fetched with an _escaped_fragment_ URL).
It won't work for #! URLs. Twitter has a nice streaming API for search if that's what you're looking for.