The source distribution can be downloaded from SourceForge.
The source distribution is a GNU-style source package that is portable to most POSIX systems with a reasonably modern C++ compiler. The source distribution also includes project files for building on Windows with the freely-available Visual C++ Express compiler.
OpenVRML is packaged for Fedora and can be installed using yum; e.g.:
$ yum install openvrml-player openvrml-mozilla-plugin
OpenVRML is packaged in FreshPorts.
The latest development sources can be checked out from OpenVRML's Subversion repository on SourceForge:
$ svn co http://svn.openvrml.org/svnroot/openvrml/trunk openvrml