Trn is "Threaded Read News", a text-mode newsreader based on Larry Wall's "rn" with a bunch of improvements, including some scaning and scoring features contribued by Cliff Adams (from his strn work).
Trn is now being hosted on sourceforge.net. To have a look around, visit its project page.
If you'd like to help out with development, register yourself at sourceforge.net, and then contact one of the Project Admins listed on the project page.
The current trn release is a "test" release mainly because the documentation hasn't been updated yet to incorporate all the changes that 4.0 incorporates. There is some on-line help and some sample files available to get you going, but just don't expect the man page to be up-to-date.
To get the very latest source, grab it via anonymous cvs. Alternately, you can grab the test77 tar file or one of the recent patch files: trn-4.0-test77.patch.gz, trn-4.0-test76.patch.gz, trn-4.0-test75.patch.gz, trn-4.0-test74.patch.gz, or trn-4.0-test73.patch.gz.
Also available is the "dist" source (including metaconfig) that the current trn-release uses to build the Configure file: dist-3.0-70-wd2.tar.bz2.