iWork: Exported PDF documents may not display drop shadows
When you create a PDF file from an iWork application, please note that drop shadows within the PDF document may not display in all PDF readers.
The drop shadows in Pages and Keynote are generated by a component of Mac OS X. When you view iWork-generated PDF files in Preview, you'll see these shadows. However, if you view the PDF with a third-party reader that doesn't use this component, the shadows will be missing.