Is it possible to work with OrientDB using C#?

Currently OrientDB supports both a REST/JSON protocol and a native binary protocol. There are Python and Javascript wrappers for the REST protocol whyle there are C and PHP wrappers for the native protocol. I don't know if a C# wrapper is in the working however looking at the specifications ( http://code.google.com/p/orient/wiki/OrientDB_REST ) writing one for C# should be straightforward. I have met in person the architect of the project at a JUG meeting and I must say that OrientDB is a very promising project. Also Luca Garulli ( the architect ) is a very available person, so you may write him if you need more information.

OrientDB has an official binary driver for .NET look here http://orientdb.com/docs/3.0.x/

Example of usage OrientDB-NET.binary

string release = OClient.CreateDatabasePool("127.0.0.1", 2424, "ModelTestDB", ODatabaseType.Graph, "admin", "admin", 10, "ModelTestDBAlias");
using(ODatabase database = new ODatabase("ModelTestDBAlias"))
{
    // prerequisites
    database
      .Create.Class("TestClass")
      .Extends<OVertex>()
      .Run();

    OVertex createdVertex = database
      .Create.Vertex("TestClass")
      .Set("foo", "foo string value")
      .Set("bar", 12345)
      .Run();
}