Stable versions of Gnus is included in the Emacs and XEmacs editors.
If you want more leading-edge versions of Gnus, I would suggest using the bzr Emacs repository.
If you want total bleeding edge Gnus, use the Gnus git repository.
git clone http://git.gnus.org/gnus.git
machine git.gnus.org login yourlogin password yourpasswordIf your password has a space in it or if you are a rebel, use
https://yourlogin:email@example.com/gnus.gitas the address and you won't need a ~/.netrc file. It's not recommended. Also the server config says
[receive] denyDeletes = true denyNonFastForwards = trueso that will, we hope, prevent unfortunate accidents.
Send e-mail to firstname.lastname@example.org to get access, especially if you had CVS committer access already.
Server setup: Apache 2 using git-http-backend. Commits go to email@example.com and firstname.lastname@example.org, prefixed with [git] and the envelope sender is git-logger. There are two (HTTP and HTTPS) Apache 2 servers but they both run git-http-backend so "smart" clients are faster for committers and anonymous readers.
Older versions of Gnus can be found in as tar files here.
An archive of patches is also available.