[This might only make sense to me – these are very short notes on the presentation Janina held on using cloth simulation in 3ds Max].
The Plane that is supposed to be the cloth needs to get a Cloth modifier. In the modifier properties both the actual cloth as well as the objects the cloth is falling unto have to be added - the later one as a collider. Also, gravity is (unlike blender) not a standard part of the scene and has to be added as a force field. These forces need to be added to the simulation as well.
Exporting an animated armature with a mesh for Unity using Blender 2.5 can be a bit of a hassle. With the armature parented to the mesh, I could either export the mesh or the armature with the animations, but never both.
Having the armature separate from the mesh seemed to have worked – I have now everything set up in Unity, both mesh and armature with animation.