TilemapKit is currently written in Objective-C and in the process of being ported to C++ / Cocos2D-X.
If you would love to have TilemapKit available for Unity, please vote for it!
TilemapKit for Unity would work similar to "Tiled to Unity" (except that it'll draw 2D tiles, not tile-able 3D models) and would have far more features than "UniTMX". With TilemapKit you'll get the same map as you see in Tiled right into Unity, including "tile to screen" conversion and back.
In addition, Pathfinding support seems absolutely feasible, both Unity's built-in and Aron Granberg's A* Pathfinding Project.
As a side-effect, this would also make the MonoGame port more viable: http://tilemapkit.idea.informer.com/proj/tilemapkit?ia=97688