In the Unity 3 beta, as far as I can tell you can only get the position of an InteractiveCloth mesh before the simulation starts. The transform never updates once the game is running. 
I’m trying to find a way to track the general position of it. What confuses me is that the Unity editor window seems to position a transform gizmo in the middle of the mesh as the game is running so something is able to track it’s position throughout the simulation (I assume it’s averaging the position of all verts in the cloth mesh) but I can’t figure out how to get that position.
The best I’ve managed to do so far is attach tiny rigidbody sphere collider in the middle of the cloth mesh with “Two Way Interaction” so it follows it around and use it’s position instead, but even with a mass of 0.01 it still effects the simulation a heap.
Has anyone figured out how to track the cloth’s general position once it starts moving?
p.s. With attached colliders, even when you set the collider’s IsTrigger property to true, it’s mass still effects the simulation. This seems wrong. You should be able to attach triggers that stick to or follow the cloth but not effect any physical properties.
It would also be nice if, scripting wise, the InteractiveCloth was more like other physics objects. Adding forces is limited to setting constants or non-standard calls. I don’t see why there aren’t any ApplyForce and ApplyTorque methods that apply forces to the entire object evenly.