One of the main features of NVIDIA APEX framework is not only complexity or quality of simulation, but artist-focused authoring pipeline, that allows easy creation of physical content without significant programmer involvement.
Update: PhysX plug-ins for Max and Maya with APEX Clothing features are available.
Update #5: New complete set of official APEX Clothing tutorials.
Following tutorials (available previously for plug-in beta users) are giving perfect overview of clothing authoring process, basic capabilities and features, using 3ds Max plug-in as an example.
Update #2: APEX Clothing tutorials for Maya added.
APEX Clothing with Maya – Trench Coat Medium
Update #3: APEX Clothing tutorial: from Maya to UDK