For information, the OL3-Cesium project which provides synchronization between an OpenLayers 2D map with a Cesium 3D globe, has been renamed.
This change is the direct consequence of the renaming of the OpenLayers3 project to “OpenLayers”.
The first ol-cesium release is v1.24.3. See https://github.com/openlayers/ol-cesium/releases/tag/v1.24.3
For a list of recent changes, please have a look to https://github.com/openlayers/ol-cesium/blob/master/CHANGES.md.