Ogre
Open source graphics renderer with Scene Management and a proprietary .mesh format for objects. Community driven with many projects using it. Ogre itself is huge and is constantly being developed. There are many changes to the latest versions of Ogre, including most of the components and sub-pages that are listed below, with the most recent ( 2.1 ) being the most changed.
Latest important Ogre news topics with regard to new versions :
http://www.ogre3d.org/forums/viewtopic.php?f=27&t=82761
http://www.ogre3d.org/forums/viewtopic.php?f=27&t=82743
http://www.ogre3d.org/forums/viewtopic.php?f=27&t=82764
http://www.ogre3d.org/forums/viewtopic.php?f=27&t=82888
Also visit 2.0+ forum for latest information
http://www.ogre3d.org/forums/viewforum.php?f=25
Ogre source code hosted at http://bitbucket.org/sinbad/ogre
You can check out all my posts related to Ogre by looking at my profile here - http://www.ogre3d.org/forums/memberlist.php?mode=viewprofile&u=27791