OpenOffice.org 2.4 introduces a new checkbox Convert document references to PDF targets. I suggest always checking this checkbox when exporting documents with file links. When exporting a PDF, it changes OpenDocument extensions (such as .odt, .ods, and .odp) to .pdf.
The change, which is only effective in the PDF, can be a time saver for those needing workable document links both in OpenOffice.org and in the PDF reader application (typically Acrobat Reader) without having to constantly edit the link extensions. In other words, this feature lets you use the same links to link to OpenDocument files from OpenDocument files and PDF files from PDF files.