Though you write PDF documents without Adobe Acrobat, there aren’t many choices for manipulating or editing PDF files. Most available PDF editors are either commercial or offer very limited functionality.
All this is expected to change with Sun OpenOffice 3 which includes native PDF import and export features.
Related: How to Edit PDF Files
You will be able import PDF files into Draw (PowerPoint), perform the edits and then export them as hybrid PDFs meaning you can edit the PDF files back again in OpenOffice.
OpenOffice 3 will be available on Windows and Mac. It may not have all the PDF editing features of Acrobat but may still satisfy the needs of most users who only require basic editing.