It has been revealed that the obscene and threatening message sent to Ann Althouse was authored by one Jim Shankman, of Madison, WI. The unemployed Shankman appears to have a Facebook page:
http://www.facebook.com/people/Jim-Shankman/651447561
However, following this link now takes us to a re-named page.
Google cache screen captures are available below, for the sake of posterity.
Update: Shankman is rolling through a variety of names on his Facebook page. It would appear Shankman has many masks. If I behaved as he does, I guess I’d where a mask, too.