While looking for something to solve a partucular problem, I came across Twisted's DeferredQueue. Although it was not what I was looking for it looked interesting so I knocked up a quick example:

import itertools
from twisted.internet import defer
from twisted.internet import reactor
from twisted.internet import task

FREQUENCY = 10

def startProducing(q):
    """Put an incrementing number in the queue every 1/FREQUENCY
    seconds.
    """
    counter = itertools.count()
    def produce():
        q.put(counter.next())
    task.LoopingCall(produce).start(1.0/FREQUENCY)

def startConsuming(q):
    """Consume an object from the queue and print it.
    """
    def consumer(o):
        print o
        q.get().addCallback(consumer)
    q.get().addCallback(consumer)

q = defer.DeferredQueue()
startProducing(q)
startConsuming(q)

reactor.run()