OpenNMS 1.10.9 is the latest in the stable series of releases. It contains a number of bugfixes and small feature enhancements, most notably a fix for remote poller startup issues when certain plugins are enabled, a CIFS monitor, an optional change to the front-page outage list, and many other tweaks. It is a recommended upgrade for all users.
OpenNMS 1.10.8 is the latest in the stable series of OpenNMS releases. It includes a number of bugfixes including collector and detector fixes, and support for the latest PostgreSQL. It is a recommended upgrade for all users.
1.10.7 is the latest in the stable series of OpenNMS. It contains a number of small bugfixes including graphing fixes, a fix for thresholding on data collection that retrieves multiple values (like StrafePing), and a few other things. It also adds support for adding user documentation/annotations on alarms.
OpenNMS 1.11.3 is the latest in the unstable series, which will eventually become the stable 1.12.x series. It includes a number of bugfixes and enhancements, including support for the CIDR route table for populating Linkd information.