On behalf of the Samba development team, Karolin Seeger released Samba 4.0 Release Candidate 1 on Thursday. "Samba 4.0 will be the next version of the Samba suite and incorporates all the technology found in both the Samba4 alpha series and the stable 3.x series. The primary additional features over Samba 3.6 are support for the Active Directory logon protocols used by Windows 2000 and above."
The 4.0 release has been talked about for a while and only in June of this year it went into beta after twenty-one alpha releases.
Developers believe Samba 4.0 is now stable, plus is backed by extensive testing, but to not count on it yet in a production environment. "Samba 4.0 is subjected to an awesome battery of tests on an automated basis, we have found Samba 4.0 to be very stable in it's behaviour. However, as with all our pre-releases we still recommend against upgrading production servers from Samba 3.x release to Samba 4.0.0rc1 at this stage."
Samba 4.0 supports the server-side of Active Directory Log-On from Windows 2000 and above, the Samba 4.0 Domain Controller implements a built-in LDAP and Kerberos Key Distribution Center, there's two distinct file servers, an NTVFS file server, and many other features to this popular open-source project.
More details can be found from the mailing list announcement.