>>> f = open('woot.tar.bz2').read()
>>> t = tarfile.open(fileobj=cStringIO.StringIO(f))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/local/lib/python2.5/tarfile.py", line 1019, in open
    return func(name, "r", fileobj)
  File "/opt/local/lib/python2.5/tarfile.py", line 1077, in gzopen
    pre, ext = os.path.splitext(name)
  File "/opt/local/lib/python2.5/posixpath.py", line 92, in splitext
    i = p.rfind('.')
AttributeError: 'NoneType' object has no attribute 'rfind'