Hello,
The only real world software rendering application I know of is for offline rendering (e.g. movie production). A typical Pixar movie, for example, takes months on vast server farms to finish rendering. However, they are not interactive animations. If you seek an interactive 3D application with high FPS, you either go to GPUs or impose restrictions on scene complexity. There is a reason why the industry invests billions on hardware accelerated rendering.
take care,
Paulo