In case you clicked on this link instead of this one, WLUG will be co-sponsoring some talks on this subject.
OpenOffice is the commonly used name for OpenOffice.org, a free office suite based on SunMicrosystems's StarOffice but released under the LGPL. The FAQ explains:
The trademark for "OpenOffice" belongs to someone else. Therefore we must use "OpenOffice.org" when referring to this OpenSource project and its software.
See OpenOffice.org for more.