Brief history of OGRE        
1999ish
Sinbad realises that his DIMClass project, a project to make an easy to use object-oriented Direct3D library, has become so abstracted that it really doesn't need to be based on Direct3D any more. Begins planning a more ambitious library which could be {LEX()}API{LEX} and platform independent.
25 February 2000
Sourceforge project registered, OGRE name coined. No development starts due to other commitments but much pondering occurs.
October 2000
Full-on design starts, refactoring of DIMClass begins.
December 2000
Major design pieces are in place, main classes like SceneManager, RenderSystem, SceneNode are all identified concepts with CRC cards to call their own
February 2001
First platform manager complete (Win32), D3D7 is now the first rendersystem
February 2001
OGRE becomes completely dynamically loaded, rendersystems & platform managers as plugins
4 March 2001
First test render of refactored OGRE system
30 March 2001
Started using Doxygen instead of ccdoc to generate API docs
1 April 2001
Made an important design decision to separate the class hierarchies of spatial structures {LEX()}SceneNode{LEX} and scene contents (MovableObject) and join them through attachment to reduce dependencies and improve flexibility
May 2001
{LEX()}Entity{LEX} / SubEntity / {LEX()}Mesh{LEX} / SubMesh system created
13 June 2001
FrameListener and FrameEvent introduced
3 July 2001
OGRE 0.6 released
17 July 2001
Moved away from 4x4 matrices in {LEX(pagename="SceneNode")}nodes{LEX} to separate position / orientation / scale, and switched to quaternions for all rotations
September 2001
Bezier patches and multitexture / multipass blending work:
November 2001
{LEX()}skybox{LEX}es, skydomes and skyplanes
December 2001
BSP support finished
14 January 2002
Controllers introduced
Feb 2002
cearny joins the core team
March 2002
OGRE 0.98b - Material scripts make their first appearance. ROAM landscape engine appears (later dropped in favour of geomipmapping). Billboards. First time STLport is required because of increased STL compliance.
April 2002
temas joins the core team
June 2002
OGRE 0.99b - Particle systems and misc stuff
September 2002
OGRE 0.99d - Linux support, OpenGL renderer, skeletal animation, Milkshape exporter, Codec structures:
October 2002
janders joins the core team
October 2002
OGRE 0.99e - XMLConverter appears, octree scene manager appears, D3D8 renderer, spline animation interpolation, font rendering via Freetype
December 2002
Mesh {LEX()}LOD{LEX}, Geomipmapping terrain, stencil operations:
January 2003
First release of Blender exporter
February 2003
OGRE 0.10.0 (version reformatted) - 3DS Max exporter, D3D9 renderer:
Mid 2003
cearny & janders leave project (inactive):
June 2003
OGRE 0.11.0 - SceneQuery added, ODE collision demonstrated in BspCollision, Maya and Wings exporters, lots of small enhancements:
May 2003
_mental_ joins the core team:
September 2003
OGRE 0.12.0 - hardware buffer interfaces, vertex declarations, complete geometry system overhaul. First time we branched the codebase into maintenance and development branches:
January 2004
OGRE 0.13.0 - major material overhaul, vertex & pixel shader support for assembler (D3D & GL), {LEX()}Cg{LEX} and {LEX()}HLSL{LEX}, XCode support:
May 2004
OGRE 0.14.0 - shadows, hardware skinning, projective texturing:
July 2004
wumpus joins the core team:
October 2004
OGRE 0.15.0 - binary mesh format made more flexible, {LEX()}GLSL{LEX} support, Radian/Degree classes, :
November 2004
SoftImage agree to sponsor the OGRE project and allow free access to XSI SDK.:
February 2005
OGRE v1.0.0 Final Azathoth released - resource system overhaul, hardware pixel buffers, HDR, CEGui, XSI exporter:
March 2005
OGRE is 'Project of the Month' on Sourceforge:
July 2005
Jeff 'nfz' Doyle joins the OGRE Team:
September 2005
Sinbad announces Kadath, a commercial scene manager and exporter tool for use with OGRE, XSI and Blender.:
May 2006
OGRE v1.2.0 Final Dagon released:
September 2006
Enrichments by Google Summer of Code 2006 :
March 2007
OGRE 1.4.0 Final Eihort Released:
April 2007
Google Summer of Code 2007 projects announced:
March 2008
Google Summer of Code 2008 student applications open:
November 2008
OGRE 1.6.0 Final Shoggoth released:
July 2009
David ‘masterfalcon’ Rogers joins the team, brings iPhone support
August 2009
Google Summer of Code 2009 projects announced
October 2009
Noam 'Noman' Gat joins the team

More information can be found in the blog of the www.ogre3d.org homepage.

To see release information (change log / history) you can use this link or have a look at the Roadmap here in the wiki.