Leafnode-1 is the stable release recommended for general use, Leafnode-2 will be a feature-enhanced version that is currently under development.
Leafnode-1 is mature and stable and IPv6 enabled. It is maintained, bugs will be fixed, but no features will be added.
The current leafnode release is 1.11.8, released 2010-06-12.
For up-to-date information on release candidates, see http://home.pages.de/~mandree/leafnode/
Leafnode-2 is under development and currently in "alpha" state. It works quite well but can undergo radical changes between releases, hence it is unsuitable for production use. The current status can be seen at http://home.pages.de/~mandree/leafnode/beta/.It supports being run as standalone server for local newsgroups (it does not support feeding though, yet) and more flexible filtering, has rudimentary UUCP support and downloads article faster since it pipelines the downloading "ARTICLE" commands. Note that leafnode-2 does NOT allow direct access to the news spool, newsreaders MUST talk NNTP (most do).