Наиболее важные фичи:
Active Directory support. Samba 3.0 is now able to join a ADS realm as a member server and authenticate users using LDAP/Kerberos.
Unicode support. Samba will now negotiate UNICODE on the wire and internally there is now a much better infrastructure for multi-byte and UNICODE character sets.
Better Windows 2000/XP/2003 printing support including publishing printer attributes in active directory.
Support for migrating from a Windows NT 4.0 domain to a Samba domain and maintaining user, group and domain SIDs.
Support for establishing trust relationships with Windows NT 4.0 domain controllers.
Full support for client and server SMB signing to ensure compatibility with default Windows 2003 security settings.