Creates map image file depending on the Create Maps Enable value in the Morrowind.INI file. If it is 1 (XBox), the file FILENAME.ESP.MAP is created in the DataFiles path with the map data (unknown format). If the value is 2 (Exterior Cell Maps) and you have created a directory /Maps/ in the main Morrowind game directory, this command will create a 256x256 high color bitmap of each exterior cell in the game. This command takes a long while even on fast computers as each cell in the game is loaded.
{Morrowind Scripting for Dummies}

Razorwing wrote a small tutorial on this, look at it HERE