Buffer objects *are* picklable with protocol 2 (but not with earlier protocols).  Unfortunately, the result is not unpicklable.  

This is not a problem with multiprocessing.  (buffer seems to inherit __reduce__ and __reduce_ex__ from object.)

Python 2.7.1+ (r271:86832, Apr 11 2011, 18:13:53) 
[GCC 4.5.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cPickle
>>> cPickle.dumps(buffer("hello"), cPickle.HIGHEST_PROTOCOL)
'\x80\x02c__builtin__\nbuffer\nq\x01)\x81q\x02.'
>>> cPickle.loads(_)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: buffer() takes at least 1 argument (0 given)