1) Why? OpenDJ 2.6 works for our purposes. Not broken... don't fix it...
2) Frankly, I don't know if we'll ever see another update to the community OpenDJ source. Although FR likes to make it look like you can get later source, when you go to download it, its not there. Ask Forgerock when they will release an open source code for something later than 2.6, and we can re-build it. We have forked the last open source release in [github](https://github.com/GluuFederation/gluu-opendj).
3) If you really want version 3 of OpenDJ, and you value it enough to pay for it, please buy it from Forgerock!
4) Also consider UnBoundID (also commercial license)--our deployment is the same for UnboundID, which I think has the best performance of all the currently available LDAP servers.