Yeah I'd definitely say we should continue to follow our established best practices until G gets better at this but Josh's evidence and our continued testing on this subject is very compelling.
On that note, I am personally of the belief that the fragments are part of Google's learning/training process for their spiders.
If they sniff the XHR traffic on every domain they encounter a HashBang they can learn lots about the use of AJAX and the types of content being exposed via AJAX.