Well...the latest consensus is that it's a fake/fantasy piece. The item, as you might have surmised, is on eBay.
As I'm not aware of an original of this poster, the question for me now is whether it is a fake/forgery or a fantasy piece.
It happens to be well-done if it's not old: note the consistency of the wear/discoloration on the front and back. Very scary if fake.
The listing is here:
http://cgi.ebay.com/ws/eBayISAPI.dll...m=370210485112