I am looking for a solid implementation of an ordered associative array, that is, an ordered dictionary. I want the ordering in terms of keys, not of insertion order.
I'm not sure which python version are you working in, but in case you like to experiment, Python 3.1 includes and official implementation of Ordered dictionaries:
http://www.python.org/dev/peps/pep-0372/
http://docs.python.org/3.1/whatsnew/3.1.html#pep-372-ordered-dictionaries