How does Posterous generate an email address for their users and when you email an attachment or content, that is posted on your posterous blog?
Just can't seem to think of how that works...
They probably have all incoming mail that doesn't match any mailboxes (e.g. a "catch-all" account) piped to a script (who knows what language, though it could certainly be done in PHP - Google "pipe mail to PHP script") that queries a database and performs tasks based on the e-mail address that the message was sent to.
