The best way to describe Racket is as an ecosystem. The analogy I would make:

   EMACS : text editor
   Racket : programming language

This is to say that Racket comes with enough batteries to make it a platform...or at least Racket is striving to achieve cradle-to-grave coverage. It doesn't just come with tutorials, but a complete programming course - How to Design Programs.

It comes with tools for building languages, creating presentations, and writing documents. No email, though (yet).

Racketeers are eating their own dog food. The Racket Way video gives a good introduction: http://www.infoq.com/presentations/Racket