$ virtualenv --no-site-packages private
New python executable in private/bin/python
Installing setuptools............done.

$ private/bin/python
Python 2.5.1 (r251:54869, Apr 18 2007, 22:08:04) 
[GCC 4.0.1 (Apple Computer, Inc. build 5367)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.prefix
'/Users/dhellmann/PythonMagazine/private/bin/..'
>>> import pprint
>>> pprint.pprint(sys.path)
['',
 '/Users/dhellmann/PythonMagazine/private/lib/python2.5/site-packages/setuptools-0.6c7-py2.5.egg',
 '/Users/dhellmann/PythonMagazine/private/lib/python25.zip',
 '/Users/dhellmann/PythonMagazine/private/lib/python2.5',
 '/Users/dhellmann/PythonMagazine/private/lib/python2.5/plat-darwin',
 '/Users/dhellmann/PythonMagazine/private/lib/python2.5/plat-mac',
 '/Users/dhellmann/PythonMagazine/private/lib/python2.5/plat-mac/lib-scriptpackages',
 '/Users/dhellmann/PythonMagazine/private/lib/python2.5/lib-tk',
 '/Users/dhellmann/PythonMagazine/private/lib/python2.5/lib-dynload',
 '/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5',
 '/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/lib-tk',
 '/Users/dhellmann/PythonMagazine/private/lib/python2.5/site-packages']
>>>