In numpy.distutils.system info:
default_x11_lib_dirs = libpaths(['/usr/X11R6/lib','/usr/X11/lib',
'/usr/lib'], platform_bits)
default_x11_include_dirs = ['/usr/X11R6/include','/usr/X11/include',
'/usr/include']
These defaults won't work on the forthcoming Ubuntu 11.10, which
installs X into /usr/lib/X11 and /usr/include/X11.
Darren