MapServer is an OpenSource development environment for building spatially enabled Internet applications. The software builds upon other popular OpenSource or freeware systems like Shapelib, FreeType, Proj.4, libTIFF, Perl and others. MapServer will run where most commercial systems won't or can't, on Linux/Apache platforms. MapServer is known to compile on most UNIXes and will run under Windows NT/98/95.
The MapServer system now supports MapScript which allows popular scripting languages such as Perl, Python, Tk/Tcl, Guile and even Java to access the MapServer C API. MapScript provides a rich environment for developing applications that integrate disparate data. If the data has a spatial component and you can get to it via your favorite scripting enviroment then you can map it. For example, using Perl's DBI module it is possible to integrate data from just about any database vendor (eg. Oracle, Sybase, MySQL) with traditional GIS data in a single map graphics or web page. In addition, there is now a PHP/MapScript module included in the current release- thanks DMSolutions.