The Array Modifier allows you create procedurally duplicated/merged Objects, to make chains, cogs, fractals or even beautiful natural shapes.

It's all fully animatable, with control-Objects defining duplication methods. Check this 4 MB movie from Matt Ebb and Campbell Barton.

The new rendering pipeline offers a wealth of new features. It has become tile-based and fully threaded, supporting advanced preview renders, layer-rendering and pass render, with a tight integration to the compositor.

Currently most 3D suites have some kind of "shader editor", typically represented as Nodes or Trees. To easily allow current Materials to become layered or combined, but also to enable a Blender-compatible migration, a hybrid version has been implemented in Blender now.

Without a doubt compositing is one of the hot topics in 3D computer graphics creation, especially to enable efficient management and creative control of complex scenes and images. Blender now offers a feature rich and flexible compositing system.

One of the results of the Render Pipeline recode was the possibility to add vector-based motion blur, as a post process available in the Compositor.

Blender uses for this a novel approach, based on turning the rendered image into a 3D model (with depth) and accumulating all motion passes into a new image.

Description of the new Node Editor and all aspects of working with Nodes and linking them.

Technical notes about the implementation of Blender's node system. This is used now for Shading and Compositing, but allows future expansion in many different areas.

While ray-tracing transparent materials, Blender now computes the length of each ray chord as it passes through an object. This length of the ray chord can be used to measure how light gets filtered progressively through the object.

Also solved was the 'total inner reflection' case, giving more realistic 'silvery-looking' appearance.

Support has been added for 16 bits or 32 bits per component graphics files. Blender now supports ILM's OpenEXR, Kodak's DPX and Cineon, and Radiance HDR.

A lot of work has been done to improve the non-linear video editor in Blender. The highlights include a much better memory management (edit up to hours near-real time) and for Linux users, FFMPEG was added for a wide range of video/audio codecs.

With the new angle based flattening, complex meshes can be unwrapped with much better results. Seam cutting tools to mark seams with a single click make it easier to cut up a mesh into charts, and the minimize stretch tool allows to reduce area distortion.

Object Grouping allows to organize work much better. It is especially useful for duplicating entire animation systems, creating custom primitive sets, or for more precise control over what light is used per Material.

The game engine new physics engine - Bullet - has been improved the past 6 months a lot.

Also new is support for loading Collada files, including support for basic physics and textures.

New Mesh modeling tools include; Merging & collapse options, better select mode conversions, Loop multi-select, Path selecting, and improved Mirror modifier.

Apart from node materials, a few assorted material features have been added, including tangent shading (to give any shader an anisotropic effect), stress maps, and new layer blending modes.

Blender's fluid simulator has had numerous updates, including support for animated (and deforming) obstacles, integration with vector motion blur, improved smoothing and particles.

A new Blender UI control allows to create a mapping from any range to a new range. It is in use now for the new Node Editor, but also as option available in the Image Window, to investigate or remap high dynamic range images.

Some features were in use during the Orange project that didn't make it in the 2.41 release. 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.

Materials, Images, Textures, Lamps and Worlds are now rendered as small icon to facilitate browsing them easier.

Many updates and additions in the API and available scripts, plus the introduction of Python button evaluation and PyDrivers.

Python scripting has been an important part of projects like Elephants Dream and Plumiferos, whose contributions, feedback and requests have in turn helped improve the API. But the usage of scripting has increased in other fronts as well, adapting and expanding Blender to produce content for different needs and to integrate it with other tools.

One of the ancient but powerful Blender features, to be able to share data from Blender files with other files, has been gathering dust for a long while. Since it's a very important feature in a production environment, it has been verified to work and fixed in many places.