Apparently, mmap_object_type.ob_type wasn't initialized properly for UNIX platforms.  The patch below fixes the problem for Linux, and I believe it should work for windows as well.

===================================================================
RCS file: /cvsroot/python/python/dist/src/Modules/mmapmodule.c,v
retrieving revision 2.26
diff -c -r2.26 mmapmodule.c
*** mmapmodule.c	2001/01/10 21:03:32	2.26
--- mmapmodule.c	2001/01/14 04:03:15
***************
*** 841,849 ****
  	int fileno;
  	HANDLE fh = 0;
  
- 	/* Patch the object type */
- 	mmap_object_type.ob_type = &PyType_Type;
- 
  	if (!PyArg_ParseTuple(args,
  			  "iO|z",
  			  &fileno,
--- 841,846 ----
***************
*** 956,961 ****
--- 953,962 ----
  initmmap(void)
  {
  	PyObject *dict, *module;
+ 
+ 	/* Patch the object type */
+ 	mmap_object_type.ob_type = &PyType_Type;
+ 
  	module = Py_InitModule ("mmap", mmap_functions);
  	dict = PyModule_GetDict (module);
  	mmap_module_error = PyExc_EnvironmentError;

Assigning to tim, because I recall seeing a checkin 
message from him saying he fixed it.

Thanks, Moshe.  I swear I closed this already, adding a note giving the new revision numbers for mmapmodule.c, test_mmap, output/test_mmap, and mentioned I'd also checked in a new ACKS.  But, indeed, there's no record of that here!  So closing it now (again, from my POV).