This is a really cool program. It used to have a learning curve like an icy cornice bowl. Hopefully the new version will be easier to learn!
Here is what Dr. Stephen Wolfram just said about it:
The most important advance in the 20-year history of Mathematica Building on two decades of world-class algorithm and software development, Mathematica 6 represents a dramatic breakthrough that immensely broadens Mathematica's scope and applicability—and redefines the very way we think about computation. Made possible by Mathematica's unique symbolic architecture, Mathematica 6 introduces a sweeping unification of language and interface concepts that makes possible a new level of automation in algorithmic computation, interactive manipulation and dynamic presentation—as well as a whole new way of interacting with the world of data.