This line at least does seem to imply that it came from their netblock (the public google.com IP addresses also begin with 216.239):
Received: from 216-239-45-4.google.com (216-239-45-4.google.com [184.108.40.206]) by fuchsia.puzzling.org (Postfix) with ESMTP id 4D2DF1016C for <firstname.lastname@example.org>; Tue, 1 Mar 2005 05:58:08 +1100 (EST)
That’s kind of … uncool. One might almost say… unsolicited commercial email.
I did get something like this once before and forwarded it to email@example.com, only to get an instantaneous automated reply telling me that any spam I was reporting could not possibly have come from them.
Perhaps it didn’t and it’s a rather more competent header forgery than most spam. The forensics will be interesting in that case.