This was exactly what I thought. Someone bypassed the MIME type at the Web site level and decided to put .pdf to be application/octet-stream. So, as is, in the old code, this was not working in Firefox and Safari. IE did not bother about that one and was showing it inline. Now, with or without that bypass which is wrong, with the object/embed code, this always work ok in IE, Firefox and Safari. Google Chrome does not have that inline support yet. So, I guess for that one a plug-in is necessary.