I mailed them but didn't get a bounce. So perhaps the message will get through.

Update. And their reply:

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Hello John,

Thank-you for the report. I have gone in and taken the post down so that it is no longer live. Julio is a contributor of our main blog and his email address was compromised and used to send that post. Posterous itself has not been compromised and the posting has been removed.

Thank-you for using Posterous and I apologize for the inconvenience.

Kathleen