I am not very experienced with LDAP and so couldn't really tell you what features beyond basic authentication are needed.
My suggestion was more general in nature, rather than something I specifically require/need. I think that features like LDAP would greatly assist in making Mango more adoptable by larger organisations and there are obvious commercial benefits that follow. If it really is not that much work to implement, it might have a pretty favourable cost/benefit ratio.
I personally would use it, but it's not something I'm really bothered about right now!
Mango is built on top of Spring and they have an LDAP component.
What features besides just a simple login authentication would you desire in such a module. We already have an Authentication "type" module that we've implemented for Crowd authentication. It wouldn't be very much work to use Spring LDAP and make a similar type of module.