Computable Document Format

I've recently become aware of Wolfram's Computable Document Format or CDF as it's referred to. It adds interactivity to documents in a manner similar to Apple's iBooks Author, that allows anyone to create interactive textbooks for reading in iBooks. You need to download the CDF player, which I've done, but it's a hefty 2.2 GB in size. With the player installed you can then open CDF files. The format is clearly proprietary and it remains to be seen how much traction it will get in the marketplace.

Here is what Wikipedia has to say about CDF:

Features 

Computable document format supports GUI elements such as sliders, menus and buttons. Content is updated using embedded computation in response to GUI interaction. Contents can include formatted text, tables, images, sounds and animations. CDF supports Mathematica typesetting and technical notation. Paginated layout, structured drill down layout and slide-show mode are supported. Styles can be controlled using a cascading style sheet. 

Reading 

CDF files can be read using a proprietary CDF Player with a restrictive license, which can be downloaded free of charge from Wolfram Research. 

Authoring 

CDF Files can be created using Mathematica. Online authoring tools are planned. 

Uses 

Computable Document Format has been used in electronic books by Pearson Education, to provide the content for the Wolfram Demonstrations Project, and to add client-side interactivity to Wolfram Alpha.

Now that I'm aware of the product I can monitor its fortunes.