The source code for the browser plugin has been released under the GNU Public License version 2 (GPL2).
The latest development version is available from SVN at http://novellab.brighton.ac.uk/svn/opensg-browser-plugin
A working snapshot has been released as version 0.1: Version 0.1 provides support for showing 3D models supported by OpenSG within the browser.
For help building the plugin visit the building page.