I've just noticed that the long, convoluted Facebook URLs that we're used to now look like this: http://www.facebook.com/example.profile#!/pages/Another-Page/123456789012345 As far as I can recall, earlier this year it was just a normal URL-fragment-like string (starting with #), without the exclamation mark. But now it's a shebang or hashbang (#!), which I've previously only seen in shell scripts