This page describes how to get the source code for MapGuide Open Source.
In order to access the source you will need a Subversion client. Information for Subversion can be found at http://subversion.tigris.org/. The client that we like to use is TortoiseSVN available from http://tortoisesvn.tigris.org/, because it provides a nice shell integration with Windows.
The location of the Subversion repository is http://svn.osgeo.org/mapguide/. From there you will find the trunk which contains the latest code, and branches that contains the current branch that we are working on (actually, we are often actively working on trunk until we get close to the release).
As an example, to get the latest code from trunk using the subversion command line client use the following command:
svn checkout http://svn.osgeo.org/mapguide/trunk/MgDev mydir
This will do an anonymous retrieval of the source code in trunk/MgDev to your local mydir directory. Note that there is also a www directory in trunk, but this directory does not contain source that is required for building MapGuide Open Source.