I just double checked with the following program:
#! /usr/bin/env python

import os
import fcntl
import socket


def isnonblocking(fd):
    
    return bool(fcntl.fcntl(fd, fcntl.F_GETFL, 0) & os.O_NONBLOCK)

def main():
    s=socket.socket()
    
    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    s.bind(("0.0.0.0", 8000))
    s.listen(5)

    s.settimeout(30)
    
    
    print "server isnonblocking:", isnonblocking(s.fileno())
    client, addr = s.accept()
    print "client isnonblocking:", isnonblocking(client.fileno())
    
    
        
if __name__=="__main__":
    main()



on my g4 mac it prints:
~/ python serv.py                                                 
ralf@mini ok
server isnonblocking: True
client isnonblocking: True


on linux:
~/ python mini/serv.py                                           
ralf@rat64 ok
server isnonblocking: True
client isnonblocking: False