Joomla 2.5.5 was just released today, with a few bugs fixed and 2 important security updates for a privilege escalation and an information disclosure issue:
High severity security issue, that allows unprivileged users to get admin access to a site running Joomla.
This is a low severity security issue that leaks internal information about the database, internal paths and PHP info.
More information about this release here: Joomla 2.5.5 released
Remember, the leading cause for web site compromises is outdated software! So as a web site owner, you have to do your part to minimize risk and keep your site (and your users) safe. Update now!
Sitecheck was also updated to alert users not running version 2.5.5 on their Joomla sites.