>>> import sys
>>> from pkg_resources import find_distributions
>>> def print_distributions(path):
...     dists = find_distributions(path, True)
...     for dist in dists:
...             print dist
... 
>>> for path in sys.path: print_distributions(path)
... 
z3c.autoinclude 0.2.1
zc.buildout 1.0.1
zope.schema 3.4.0
zope.configuration 3.4.0
zope.interface 3.4.1
zope.dottedname 3.4.2
setuptools 0.6c8
zope.testing 3.5.1
zope.event 3.4.0
zope.i18nmessageid 3.4.3
zope.deprecation 3.4.0
WebHelpers 0.2.1
Routes 1.5