Yesterday me and David just started working on the data mapper for OrientDB, pretty inspired by Doctrine2 ORM and MongoDB ODM.
As far as I feel, things are really going smooth for now and, as you can see, you are already able to map POPOs with proper annotations, which are parsed using Doctrine annotation library.
For now, the mapper is able to hydrate single records and collections, and some type casting has been done ( you are currently able to cast to boolean, string and datetime objects ).
The query builder will probably be finished in the next 2 weeks ( some SQL indexes operators are missing and, most important, integration tests ), while in the binding, thanks to Daniele Alessandri, the HTTP response class has been polished and improved.