Moodle 1.9.1 was recently released and is recommended as an upgrade for all Moodle users.
There were no security bugs but over 400 issues were dealt with and there are a few minor new features, such as support for captcha during email registration. Thanks very much to our core team doing most of the work, as well the generous support of the community who helped with testing and reporting. See the release notes for some highlights.
As always, get it from the download page or your local CVS mirror.
Cheers,
Martin (martin)