There are several companies that make Lotus Notes newsreaders. These newsreaders allow users to browse newsgroups and post articles using the Lotus Notes interface. Generally, an NNTP host must be provided for the Usenet News gateways.
Lotus InterNotes News (now included with Notes 4.6)
Jsoft Technologies Notes<->Usenet Gateway
Mike Watson's one-way Notenews Gateway for OS/2