In Communicator and its clones, the idea was to integrate a bunch of Internet protocols and applications into a common framework. Eventually the boundaries would blur, and the tools we'd use to produce and consume documents and applications would be the same ones we'd use to communicate with individuals and groups. Unfortunately, this marriage of the web and messaging components, which was promised in the 4.x browsers, is still not yet consummated. NNTP is a powerful and accessible way for groups to create, share, find, and discuss rich hypertextual documents. These capabilities make NNTP conferencing a killer application for knowledge exchange on the intranet.
Discussion is the essential groupware application, distinct from email and complementary to it.
If you haven't yet enabled this mode of communication in your company, I urge you to do so now. Do it in the fastest, cheapest, most expedient way. The right answer for you might prove to be a so-called proprietary solution, such as Notes, Exchange, or FirstClass. Or it might be an open Internet-style solution based on NNTP or Web conferencing. Either way, what ultimately matters is that you empower your people to collaborate this way, not what flavor of software supports the collaboration.