A post Launching the Computable Document Format (CDF): Don’t Compress the Idea, Expand the Medium at the Wolfram Blog explains why CDF is so important, and it points to some nice examples of its use. If you find that mapping your high-dimensional thoughts onto a 1-dimensional line (i.e. a traditional static document) destroys most of the information, then CDF is for you (i.e. an interactive dynamic document). I have always found that using Mathematica - the engine under CDF's hood - has given me an enormous advantage over my peers who used "A N Other Product", because it allows me to do literate programming and lots more in a unified way. However, I always ended up rewriting everything in traditional 1-dimensional style to communicate with other people - usually not very successfully. CDF changes the game because it allows me to present material in the natural form in which it was created in the first place. Not only that, the interactivity of CDF it makes it much easier for the reader to understand what you are saying/doing. My previous post contains some practise runs at using CDF, though I'm sure I will do better after I have studied the Wolfram's examples of CDF use.
What about long-term archiving of material? Will CDF be around in 10 (or 100) years? As far as I know, the only "complete" and "open" document format with a long track record is TeX/LaTeX, so that is my preferred choice to ensure my place on the "dusty shelf" in perpetuity. Sometimes, I even print things out on paper!