As one whose path of the Perl learning curve was helped considerably by close study of merlyn's Web Techniques articles, I think this a really good idea, but I think that it's good in a non-obvious way: The act of writing narratives for code can help the code itself.

Finding that a section of code is hard to describe in prose is often a good indication that the code needs reworking. It's like walking someone through your code. I often come across places where I have to say "Hm... It would have been clearer if I'd written..."

I've gotta believe that would help some of the code that gets posted.