Combine multiple print jobs into one single PDF document

This thread should help:

http://discussions.apple.com/thread.jspa?messageID=8033604&%238033604

See if any of these help:
http://publicobject.com/2007/04/pdf-printer-for-mac-os-x.html
http://www.colorpilot.com/spool_article.html
http://www.jwwalker.com/pages/pdf.html

You cannot print several documents to a single PDF file directly, but you can print them to an application that will join them. I have used the freeware PDFLab for that purpose. It is not fully 10.5 compatible, but it will work for this purpose.

In order to do it, you need to install PDFLab, and then in the Print... dialog, click on the PDF button and select Edit Menu... and in the list of workflows, choose +. In the open dialog that comes up, navigate to where you have installed PDFLab. Then for each of your documents, choose PDFLab from the PDF button, and they will be added in order. Finally, go to PDFLab and save your PDF document. This may work with other applications besides PDFLab.

Note that you can now combine and rearrange PDF files by dragging them into the sidebar of Preview. However, trying to combine them in Preview as you print just opens more and more windows, which cannot be saved into a single file, except by dragging the pages into one common sidebar.