test_socket fails randomly in about 1 of 50 iterations (MacOS X 10.5.5 
intel):

$ for ((;;)); do DYLD_FRAMEWORK_PATH=/Users/martina/Downloads/Python-
3.0rc3: ./python.exe -E -bb ./Lib/test/regrtest.py -l test_socket;done
test_socket
1 test OK.

...

test_socket
test test_socket failed -- Traceback (most recent call last):
  File "/Users/martina/Downloads/Python-3.0rc3/Lib/test/test_socket.py", 
line 121, in _tearDown
    self.fail(msg)
AssertionError: [Errno 57] Socket is not connected

1 test failed:
    test_socket
test_socket
1 test OK.

...