I've got a first version Duplicate Article Detector in place. It's active when you preview an article. Along with regular error detection and auto categorization, a search will be done to see if your article title is similar to titles of articles posted recently. Any similar titles found will be listed along the screen name who posted it and the age of the article (since posted, in days). The title comparision is done by the MySQL database engine. It's done the same way that article searches are done on the Latest Articles page, except that only titles are compared, not article content. Only titles that score above a certain value when compared to the title of your article are listed. Site Administrators can vary this cutoff value on the administrative page, though the default which I determined in testing might be fine. I plan for there to be very rarely be more than 2 candidate articles listed.
By default, only titles up to 14 days old are searched, so any matching titles that are older than that won't show up. Site Admins can modify this age cutoff as well.
Feedback is appreciated. Again this is its first debut, so modifications and bug fixes may well be in order. Thank you.