Mark my words, friends: this will be the version that is going to propel Blender into the professional world. The features that have been added since 2.41 (mainly thanks to Elephants Dream) will allow 3D and video professionals to embed Blender into their workflow.
The full changelog is extensive so I'll only cover a few highlights here
- A new render pipeline with a wealth of new features such as: 128 bits image buffer, rendering in different passes, better memory management, live render preview, tile based rendering
- Node editing systems for compositing and materials.
- The sequence editor has been completely redone: better memory management (you can now edit full movies), SPEED, chroma vectorscope and luma waveform windows, FFMPEG support for Linux.
- New Mesh tools: merging & collapse options, better select mode conversions, Loop multi-select, Path selecting, and improved Mirror modifier.
- Support for anisotropic materials.
- Improved fluid simulation which can now also handle moving obstacles.
- Better character animation tools. This includes "Custom Bones", to create useful 3d interfaces to manipulate Armatures, and support for "Bone Layers", allowing you to organize a rig much better.
For the full overview, please check out the 2.42 changelog which, I must say, has become a solid piece of documentation during the last releases. Excellent work, everyone!