Just weeks after the release of Joomla 1.0.14, another release is out, but the advice is the same: Upgrade Now!
The Joomla! Project now announces the immediate release of Joomla! 1.0.15 [Daytime]. This release addresses a security vulnerability and it is recommended that you upgrade immediately. Begin by testing on a backup copy of your site. Once you have verified that your site works as expected, backup your live site and upgrade as soon as possible
Sounds serious- better upgrade today!