I will use this opportunity for yet another shameless plug of my wiki2xml tool:
http://tools.wikimedia.de/~magnus/wiki2xml/w2x.php
You can generate several output formats, including ODF (OpenOffice etc.) from wikisource, or from a list of pages in a Wikimedia project.
The conversion is not exactly flawless, and some elements (e.g., math) are not converted, but it should give you a decent starting point.
Magnus