The Original version is a Blend file that can be seen directly on 3D viewport, much bigger and smoother than the video above:
(new download location) 4shared.com/file/84002265/f9edf23f/toolbox_materials-window_gadgets_2.html

PNG describing other features not included in the video, the materials window, and other elements:
imagebam.com/image/1ef4f29075086/

Further description of Materials window behavior on this video:
vimeo.com/2531167

Video describing toolbars' behaviour:
vimeo.com/1263746

Some Benefits:

Toolbox

- Only one but flexible method to arrange tools in 3D view. Unifies header, sticky toolbars and floating toolbars (maybe panels too).
- "Gadget-oriented" tools let users customize the distribution of these tools on the screen, and save space making visible the different gadgets only when needed. Gadgets don't need a full window dedicated to them being displayed all the time like when these tools are in the Buttons Window.
- Gadgets don't necessarily need to follow a specific design style (i.e. Buttons Window style), although they could.
- Gadgets optimized for specific tasks could be developed as plug-ins.
- Toolboxes can hold (as a copy cache) values, objects, textures, materials, constraints, modifiers, etc. in a graphical way, and let drag and drop them in any applicable situation.
- Toolboxes can be made intangible, to be able to click through it and without it getting in the way, or to mimic some applications that have icons "floating" at the sides of the window (making the toolbox transparent also)
- Drag and drop workflow, letting the users drag materials, constraints, modifiers, and other properties from one object to another, directly in the 3D view. Or apply materials to a vertex group simply dragging one to the other.

Materials Window

- Drag and drop workflow for many actions.
- Quick access to all materials from the selected object. Quick access to all textures in that object too. And also all materials and all textutes in the Blend file.
- Materials and textures displayed to the users as small previews instead of buttons with the name of the texture/material.
- Number of textures in a material are not limited by the interface space, they are displayed in an infinite strip (not sure if right now the interface is what limits the slots number).
- The options of the different render engines organized in different tabs. This lets the users keep different values for each engine, and display the options of each engine in its own dedicated space, organized as each render engine needs. If a new render engine is installed it simply gets its own tab.

(note: toolboxes and gadgets are not meant to replace the Buttons Window.)

Blenderstorm idea #532:
blenderstorm.org/qapoll/ideas/idea/532/

Blender.org discussion thread:
blender.org/forum/viewtopic.php?t=14130