I've added a new class to the repository, ArcInfoASCGridExporter, that allows for easy export of grid data to ArcInfo/Grid format. I've modified one of the demos, "turkana", to demonstrate how to use this class to automatically export grid data when a simulation finishes running.
Note that I've not released a new version of GeoMason that includes this. I need to repair the broken Shape file exporter first before I feel comfortable in cutting a new version.