As you have just seen from the last posting, the DM news server is now able to post to the list. There is also a web-based form that allows you to submit (and preview) news items http://www.digitalmedievalist.org/newitem.cfm (if you have disabled popups in your browser, you may find the bottom "preview" button doesn't work; the one at the top of the form does). The server posts the headline to the list, and the RSS feed is available for syndication.
Let me encourage you to use this service to announce -new software, -conference, book or journal calls for papers -upcoming symposia or lectures -new publications (CD-ROMs, Books, special issues of journals, etc.)
In general, these announcements should be non-commercial in nature and be submitted by the author of the announcement. Please do not repost announcements unless you have permission from the original author, and do *not* submit copyrighted feeds from other sources (e.g. newspaper articles). Submissions are mailed to the DM editors who have final say concerning publication.
-dan