On July 10th, OpenDS 1.0.0 the open source LDAP directory service in Java was released. In the release notes, the list of platforms on which OpenDS has been qualified is quite long but does not mention Mac OS X.
Many OpenDS developers have a MacBook (Pro) and use it for development, unit tests and first integration tests.
So OpenDS 1.0.0 works really well on Mac OS X with either Java 5 and Java 6.
OpenDS is now listed on Apple Mac OS X Downloads site, in the Unix and Open Source category.
Ludo Sketches 
Did you see this post http://duckdown.blogspot.com/2008/07/active-directory-20.html
Great insight into Active Directory. Too bad Sun is not at the table…
Yes, I did see it.
Sun’s directory is mentioned, as often the source of identity data in Fortune 500 companies. Is that an oddity ? It might well be a question of economics.
I likewise installed OpenDS on my Mac…..