Adobe publishes the PDF standard in its entirety and makes it available for free, without restrictions, to anyone who cares to use it," Adobe Senior Director of Public Policy Michael Engelhardt wrote last year in a letter to a Massachusetts state senator. "No one needs permission from Adobe to build their own product with the PDF standard.
Unless of course you are Microsoft and want to put it in Office 2007. Then Adobe strongarms you to take it out of Office. So you offer it as a downloadable patch. Except that upsets Adobe's apple cart and they want you to charge for it. After all, if end users can save to PDF out of Word, who will buy Adobe's overpriced and bloated Acrobat?