Mathematica is an expensive commercial application sold as software for "interactive technical computing". In particular, the product centers around the Mathematica programming language which is a very powerful and dynamic language based upon term rewriting with excellent graphical capabilities and a wealth of useful functionality in its standard library. However, Microsoft's new F# programming language not only provides most of the useful functionality found in Mathematica but has many other benefits, not least that it is completely free!
Full Article on F# News
F# is looking increasingly interesting. The fact its a functional language that automatically benefits from the .NET common library and the many third party libraries written in C# seems like a significant advantage. Its syntax is also less off-putting than Erlang for someone coming from a C/Java/C# background.
Many financial institutions are starting to incorporate .NET into their technology stacks*, so its probably an easier sell than other functional programming languages. Anything that gets those quants off of Mathematica and C will make us happy. :-)* Although we see this primarily for UI development.