MathMap , like GMIC is sort of a program within Gimp after it is installed you will find it under Filters/Generic/Mathmap.With MathMap you need only to add certain types of scripts to your Mathmap folder and they will run.You can also create your own.But enough about it's use there are many tutorial areas out there to explain to you how to use it.More information can be found here along with the latest version.
http://www.complang.tuwien.ac.at/schani/mathmap/

It is available for Linux and Windows.This is the tutorial for the Windows install.

After you download the setup file run it.
MathMap will install an mathmap.exe file into your plug-ins folder and various DLL files it needs to function properly.
It will also install a folder named MathMap into your C:\Documents and Settings\USER\.gimp-2.6 folder.
This is where you can add more scripts for MathMap.

The filter will be found under Filters/Generic/MathMap
To use it just open any image and run any of the filters listed under the Mathmap sub menu there are many!

Enjoy MathMap!