Reticule is an NNTP server, but not a Usenet News server.
Usenet is a bunch of news servers connected together via various means. They generally allow people to post articles to them, and they have rules for how these articles are passed along to other servers. You might think of Usenet as a pretty loose, massively redundant (yet still somewhat fuzzy) distribution system, with no controlling central system.
This is not what Reticule does. Reticule is the future news server to be used by Gmane. Gmane is basically a bidirectional mail gateway. It has one single article injection point, and is organized as a hub around this single server.
Reticule supports all the normal NNTP commands, so all news clients can be used to connect to Reticule servers. However, internally Reticule is quite different from other news servers.