As a developer, I was quite excited to learn that Office "12" will allow you to save documents as PDF/XPS. Since that moment, I have been quite surprised to see excitement around that feature. I am now happy to learn more about XPS. You should read Jeff Bell's blog and Andy Simonds's blog to learn more about this.
For those of you who have been asking through my blog and email if this functionality (Save As PDF) is going to be exposed in the API the answer is YES! Office PIAs will have methods that expose this functionality. The details and sample code will be available after we ship Beta 2.