Hello,
here is another proposal to enhance humanoids robots support in ROS.

When dealing with legged robots, one very important information is the
list of valid contact zones, i.e. the zones which can safely support the robot.
Information about soles are also required to generate walking trajectories.
An example of this would be http://hal.inria.fr/docs/00/46/41/25/PDF/paper.pdf.

I suggest adding to the <link> element of URDF an optional node
called "contact" which structure is very close to the geometry and
collision elements.

The attached document specify how this could be implemented.

If you feel like this should be a REP, I can adapt this draft document
to the REP format.

If this new node is accepted, I can provide a set of patches for the
urdf, urdf_interface
and urdf_parser packages.

Best,
-- 
Thomas Moulard