The document conversion scripts use the unoconv package to convert to DOC, DOCX, HTML, ODP, ODS, ODT, PDF, PPT, PPTX, RTF, TXT, XLS and XLSX. The unoconv package is available in Ubuntu 12.10 and Fedora 18 (and probably every other distribution out there) default repositories and is required for the scripts to work properly.
Next thing to do is download the script and put the contents of the downloaded folder under ~/.local/share/nautilus/scripts for Nautilus 3.6
Of course, you can always use LibreOffice to convert any document you want, but with the conversion scripts you can select multiple documents and do the job in a simpler and faster way. A nice to have option that will cost you 1 minute of your time to install and 2.5 kb of hard disk space!