April 19th, 2013. OpenNebula 4.0 RC (3.9.90) is a feature-complete preview of the upcoming OpenNebula 4.0. This release fixes most of the bugs reported since the Beta release and brings some features that did not make in the Beta release, like for example more VM operations and the new Sunstone views to customize the GUI for different users or user groups, so the interface implements the provisioning model for each role. Sunstone views replaces the 3.x self-service portal. You have all the details in the OpenNebula 4.0 RC Release Notes.
OpenNebula 4.0 includes new features, like a complete facelift of the web interface (Sunstone), NIC hotplug, VM action scheduling, VM snapshotting, more consistent action naming, outsider VMs tracking (wild and zombie VMs), new drivers for Ceph backends, and a myriad of bug fixes and minor enhancements.
Although this release is considered stable, we are still fixing some bugs and it is aimed at testers and developers to try the new features. Your feedback is more than welcomed for the final release.