It is very useful to be able to save as a PDF file a Word document or a PowerPoint presentation. The PDF format is practically universal and normally does not allow for changes (you would need Adobe Acrobat Professional to do it, if the PDF allows it).
The option to save to PDF was not automatically installed with Office 2007, so maybe you think it’s not possible because you don’t see it in the “Save as” options. You need to go to the Microsoft site and download the appropriate Add-In, called Microsoft Save as PDF for Office 2007.
Once you have installed the component, you will have a new option under “Save as”.
Rumors have it that the next Service Pak for Office 2007, called SP2 that is scheduled for release on April 28, 2009, will have native support for the PDF format.
In fact, the service pack released a few days after this post does add this feature, so make sure you upgrade to SP2, using the Windows Update service.