[Samba] what the AD support in 3.0 means?

[Farkas Levente]

hi,
what is the following sentence from "WHATS NEW IN Samba 3.0 alpha21" means:
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Active Directory support. This release is able to join a ADS realm
as a member server and authenticate users using LDAP/kerberos. 
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what I would like to do is a samba as domain contorller (PDC for win9x 
and domain contorller w2k professional sp3) but there is also a few w2k 
server. is it possible to use samba with ldap as domain contorller?
(like an AC if I run w2k server? or what kind of features can't be used 
when I use samba with ldap as domain contorller?
do I need samba 3.0 or can I do it with 2.2.7?
thank you for your help in advance.
yours.