Some of the changes to Python's build process and to the C API are:
- Three new convenience macros were added for common return
  values from extension functions: Py_RETURN_NONE,
  Py_RETURN_TRUE, and Py_RETURN_FALSE.
  (Contributed by Brett Cannon.)
 
- Another new macro, Py_CLEAR(obj), 
  decreases the reference count of obj and sets obj to the
  null pointer.  (Contributed by Jim Fulton.)
 
- A new function, PyTuple_Pack(N, obj1,
  obj2, ..., objN), constructs tuples from a variable
  length argument list of Python objects.  (Contributed by Raymond Hettinger.)
 
- A new function, PyDict_Contains(d, k),
  implements fast dictionary lookups without masking exceptions raised
  during the look-up process.  (Contributed by Raymond Hettinger.)
 
- The Py_IS_NAN(X) macro returns 1 if 
  its float or double argument X is a NaN.  
  (Contributed by Tim Peters.)
 
- C code can avoid unnecessary locking by using the new
   PyEval_ThreadsInitialized() function to tell 
   if any thread operations have been performed.  If this function 
   returns false, no lock operations are needed.
   (Contributed by Nick Coghlan.)
 
- A new function, PyArg_VaParseTupleAndKeywords(),
  is the same as PyArg_ParseTupleAndKeywords() but takes a 
  va_list instead of a number of arguments.
  (Contributed by Greg Chapman.)
 
- A new method flag, METH_COEXISTS, allows a function
  defined in slots to co-exist with a PyCFunction having the
  same name.  This can halve the access time for a method such as
  set.__contains__().  (Contributed by Raymond Hettinger.)
 
- Python can now be built with additional profiling for the
  interpreter itself, intended as an aid to people developing the
  Python core.  Providing ---enable-profiling to the
  configure script will let you profile the interpreter with
  gprof, and providing the ---with-tsc
  switch enables profiling using the Pentium's Time-Stamp-Counter
  register.  Note that the ---with-tsc switch is slightly
  misnamed, because the profiling feature also works on the PowerPC
  platform, though that processor architecture doesn't call that
  register ``the TSC register''.  (Contributed by Jeremy Hylton.)
 
- The tracebackobject type has been renamed to PyTracebackObject.
 
- The Windows port now builds under MSVC++ 7.1 as well as version 6.
  (Contributed by Martin von Loewis.)
 
See About this document... for information on suggesting changes.