Announcing MDB C++ wrapper
http://code.google.com/p/libglim/source/browse/trunk/mdb.hpp
The wrapper adds Boost Serialization, iterators and triggers to the mix.
Any serializable class can be used as a key or a value.
Triggers can be used to maintain indexes.
Notice that there is an MDB issue triggered when using this wrapper
( http://www.openldap.org/its/index.cgi?findid=7448 ), use at your own risk.