Dennis Krul

I just discovered that OpenLDAP now supports multimaster replication! This means there finally is a serious enterprise-ready(?) and open alternative for the Netscape directory server family (on which both Fedora DS and Sun JES are based iirc). Without multimaster replication it is impossible to create a real redundant directory setup, which is what you want when your whole data center depends on LDAP for authentication/authorization or other types of lookup maps. (Well, you could always just replicate the directory, but you would not be able to change anything in it while the master server was down.)
From the OpenLDAP roadmap:

OpenLDAP 2.4 (released October 2007)

Functional enhancements and improved scalability:

• Updated slapd dispatcher
• MirrorMode and MultiMaster replication
• Proxy Sync replication
• Expanded monitoring
• Multiple new Overlays
• Expanded documentation
• New socket backend (experimental)
• LDAPv3 extensions:
  • LDAP Chaining Operation support
  • LDAP Don’t Use Copy Control support
  • LDAP Dynamic Directory Services (RFC2589)
  • LDAP Transaction support (work in progress)