The Sieve Working Group web page at IETF has up-to-date information on the Working Group goals, milestones and links to the current Internet Drafts.
The tools.ietf.org Sieve WG page shows up-to-date status of various WG drafts.
The documents page in sieve.info contains static information about WG drafts.
Internet drafts on Sieve are discussed on the MTA Filters mailing list at ietf-mta-filters /at\ imc.org.
Subscription requests can be sent to ietf-mta-filters-request@imc.org (send an email message with the word “subscribe” in the body).
More information on the mailing list along with a WWW archive of back messages is available at http://www.imc.org/ietf-mta-filters.
At present, there is no mailing list or newsgroup for end users of Sieve.