I promise this is not an April Fool's joke.
Moodle 1.9.8 and Moodle 1.8.12 were recently released. Apart from a range of bug fixes and small improvements, nine security vulnerabilities (2 critical, 5 major and 2 minor) have been discovered and fixed since Moodle 1.9.7. (Thanks as usual to the reporters and to all the team responsible for fixing and publicising these serious issues).
WE RECOMMEND ALL MOODLE SITES UPGRADE THEIR SITES TO ONE OF THESE VERSIONS AS SOON AS POSSIBLE.
As per our usual release procedure, all 46,000 admins of registered Moodle sites were already privately notified nearly a week ago.
Upgrading from 1.9.7 or 1.8.11 should be a very straightforward affair for most Moodle users, but you may have login issues if you are using a custom authentication method. Full details about the releases can be found in the Moodle 1.9.8 release notes and the Moodle 1.8.12 release notes.
The releases themselves are available, as always, from our downloads page or any of our CVS mirrors.