I use Python for shell scripting a lot. Ignoring all of the issues people have brought up here, I really like how function composition is piping:

  # sort this directory by biggest file
  print sort(du("*", "-sb"), "-rn")

  # print the number of folders and files in /etc
  print wc(ls("/etc", "-1"), "-l")

The reason that I like that method over, say, envoy's [1] method is that envoy.run('uptime | pbcopy') has what I consider code in strings. When I'm writing a script, the programs I'm calling, and how they interact, is part of the "code" to me. I would prefer that they're at the language level, and not represented as strings.

[1] I only just learned about envoy in this thread. Thanks! Sadly, one of the places where I run my Python scripts is a location where I can't install my own packages, and I don't want to deal with using my own install of Python, so I tend to just implement something like this:

  def checked_exec(seq):
    p = Popen(seq, stdout=PIPE, stderr=PIPE)
    stdout, stderr = p.communicate()
    if p.returncode != 0:
        print 'err: ' + stderr
        print "'" + seq + "' failed."
        sys.exit()
    return stdout