Looking into this a bit more and reading the documentation (sorry, I 
picked this up because I know something about win32 and not because I 
know multiprocessing), it looks like a connection is supposed to be 
message oriented and not byte oriented so that a recv() should return 
what is sent in a single send().  This is like how Queue works in the 
threading case.  Note that I think the method signature when using the 
dummy.connection differ when using pipe_connection and that the two 
differ in what happens when several send_bytes's occur before a recv_bytes

I'm currently leaning toward essentially leaving the current behavior 
(and documenting it) though maybe with a better exception and 
documenting that large byte arrays can't be sent through the pipe. 
What's still an issue is if a pickle ends up being too large.