The latest version of Samba can be downloaded from Softpedia
Samba, an app that seamlessly integrates Linux/Unix servers and desktops into Active Directory environments using the winbind daemon, is now at version 4.0.1.The first maintenance release is in the 4.x branch and it contains all of Samba's technology parts, both a file server, which can be upgraded from existing Samba 3.x releases, and the AD domain controller previously known as ‘samba4.’
According to the developers, in AD, Access Control Entries can be assigned based on the objectClass of the object. If a user or a group of users is a member or has any access based on the objectClass, then that user has write access to that object.
Additionally, if a user has write access to any attribute on the object, they may have access to write to all attributes.
Check out the official announcement for a detailed description of the update process and various other changes in the software.
Download Samba 4.0.1 right now from Softpedia.