As I'm sorting out how to get ROS working well with Archlinux, one of 
the main issues is that 'python' is linked to python3 in arch.

There is a PEP addressing this issue in general 
http://www.python.org/dev/peps/pep-0394/ which in short recommends that 
python should be called via python2 or python3 unless the code is 
compatible with both.