httpwebwitch - 11:50 pm on Oct 8, 2009 (gmt 0)

Consequently, webmasters should start including hashed URLs in their sitemaps - ones with a #! to allow bots to request pages directly with predetermined AJAX content.

And I don't believe it's a coincidence that #! is a Unix "hash-bang", a 2-character command indicating that the contents of a file is a script which should be executed.