Most likely this is a case of S3 being unresponsive. Following the instructions in the text-box made of exclamation points to be thorough.
 

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    An unexpected error has occurred.
  Please report the following lines to:
   s3tools-bugs@lists.sourceforge.net
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Problem: S3RequestError: Request failed for: /
S3cmd:   1.1.0-beta3

Traceback (most recent call last):
  File "/usr/local/bin/s3cmd", line 1800, in <module>
    main()
  File "/usr/local/bin/s3cmd", line 1741, in main
    cmd_func(args)
  File "/usr/local/bin/s3cmd", line 92, in cmd_ls
    subcmd_buckets_list_all(s3)
  File "/usr/local/bin/s3cmd", line 105, in subcmd_buckets_list_all
    response = s3.list_all_buckets()
  File "/usr/local/lib/python2.6/dist-packages/S3/S3.py", line 194, in list_all_buckets
    response = self.send_request(request)
  File "/usr/local/lib/python2.6/dist-packages/S3/S3.py", line 600, in send_request
    return self.send_request(request, body, retries - 1)
  File "/usr/local/lib/python2.6/dist-packages/S3/S3.py", line 600, in send_request
    return self.send_request(request, body, retries - 1)
  File "/usr/local/lib/python2.6/dist-packages/S3/S3.py", line 600, in send_request
    return self.send_request(request, body, retries - 1)
  File "/usr/local/lib/python2.6/dist-packages/S3/S3.py", line 600, in send_request
    return self.send_request(request, body, retries - 1)
  File "/usr/local/lib/python2.6/dist-packages/S3/S3.py", line 600, in send_request
    return self.send_request(request, body, retries - 1)
  File "/usr/local/lib/python2.6/dist-packages/S3/S3.py", line 602, in send_request
    raise S3RequestError("Request failed for: %s" % resource['uri'])
S3RequestError: Request failed for: /

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    An unexpected error has occurred.
    Please report the above lines to:
   s3tools-bugs@lists.sourceforge.net
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!