Not quite, all PDF links posted have a [Scribd] tag appended to their titles that links to a scribd mirror. However in this case the original PDF is hosted on scribd, the OP got the link from an Arstechnica article.

Usually I can click the left part of the URL for the original PDF, in this case it is just a scribd URL and when I go to it the contents is blank in this browser sadly and I can't read it. My hunch is that if a PDF URL is submitted to HN it automatically adds a scribd link to the right if it can leaving the original to the left, which is snazzy and nice for those that use scribd, but that in this case it was the scribd URL itself that was submitted.