What's the shebang (#!) in Facebook and new Twitter URLs for?
It usually comes straight after the domain name.
I see it all the time, like in Twitter and Facebook urls.
Is it some special sort of routing?
# is the hash of the location; the
! the follows is used by search engines to help index ajax content. After that can be anything, but is usually rendered to look as a path (hence the
/). If you want to know more, read this.