Maybe I'm using it incorrectly, but my first attempt to use it failed:

gdb) b PyEval_EvalCodeEx
Breakpoint 1 at 0x80fc51d: file Python/ceval.c, line 3020.
(gdb) c
Continuing.
1+2

Breakpoint 1, PyEval_EvalCodeEx (co=0xb7d86928, globals=Traceback (most recent call last):
  File "/home/martin/work/27/python-gdb.py", line 574, in to_string
    return stringify(proxyval)
  File "/home/martin/work/27/python-gdb.py", line 526, in stringify
    return repr(val)
  File "/home/martin/work/27/python-gdb.py", line 271, in __repr__
    for arg, val in self.attrdict.iteritems()])
AttributeError: 'FakeRepr' object has no attribute 'iteritems'
, locals=<unknown at remote 0x0>, args=0xb7d7eb00, argcount=1, kws=0x0, kwcount=0, defs=0x827c9b0, defcount=1, closure=<unknown at remote 0x0>)
    at Python/ceval.c:3020
3020            register PyObject *retval = NULL;

This was with the Python 2.7 trunk.