Yesterday, I contacted PMI to get a green light for a book I've been writing.  Because it's referencing the PMP, I'm taking several steps to ensure I follow the rules.  My first step was to agree to abide by the PMI Intellectual Property Proper Use Guidelines.  My second (indirect) step was to request permission to link to their site.  You'd think they would want every PMP linking to their site.  Still, a link does not constitute an endorsement from them.  If anyone out there has already published materials with a PMI blessing, I would love to hear from you.