HyperNews is one of the open source web discussion systems that we have customised for D3, selectable from within the D3E Publisher's Toolkit.
See the demonstration article for an example of a document using D3E-HyperNews (where you can post test comments).The Journal of Interactive Media in Education is the most extensive example of D3E-HyperNews in use (for online journal peer review). D3E-HyperNews features:
Software: known to run on Apache and Netscape web servers; written in Perl
Hardware Platform: Unix or Linux (it makes use of unix directory file structures; no Windows port available; see D3E-Phorum for a Windows-based web server discussion environment)