Terminal 1:
Python 2.6.1 (r261:67515, Apr  2 2009, 18:25:55)
[GCC 4.1.2 20071124 (Red Hat 4.1.2-42)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from multiprocessing.managers import SyncManager
>>> manager = SyncManager(authkey="mykey")
>>> manager.start()
>>> queue = manager.Queue()
>>> import pickle
>>> pickle.dump(queue, open("myqueue.pkl", "w"))
>>>

Terminal 2:
Python 2.6.1 (r261:67515, Apr  2 2009, 18:25:55)
[GCC 4.1.2 20071124 (Red Hat 4.1.2-42)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket
>>> socket.setdefaulttimeout(30)
>>> import multiprocessing, pickle
>>> multiprocessing.current_process().authkey = "mykey"
>>> queue = pickle.load(open("myqueue.pkl"))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "python2.6/pickle.py", line 1370, in load
    return Unpickler(file).load()
  File "python2.6/pickle.py", line 858, in load
    dispatch[key](self)
  File "python2.6/pickle.py", line 1133, in load_reduce
    value = func(*args)
  File "python2.6/multiprocessing/managers.py", line 845, in RebuildProxy
    return func(token, serializer, incref=incref, **kwds)
  File "python2.6/multiprocessing/managers.py", line 894, in AutoProxy
    incref=incref)
  File "python2.6/multiprocessing/managers.py", line 700, in __init__
    self._incref()
  File "python2.6/multiprocessing/managers.py", line 749, in _incref
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "python2.6/multiprocessing/connection.py", line 140, in Client
    answer_challenge(c, authkey)
  File "python2.6/multiprocessing/connection.py", line 376, in
answer_challenge
    response = connection.recv_bytes(256)        # reject large message
IOError: [Errno 11] Resource temporarily unavailable
>>> 

This works as expected without socket.setdefaulttimeout(). However, the
timeout is useful since if the listening process on terminal 1 goes to
sleep, e.g. ^Z, it would avoid blocking.

I suspect the cause is similar to http://bugs.python.org/issue976613