The meaning of dict.keys, etc, will not change for the 2.x series. For 3.0, I believe that Guido already intends that .keys() no longer return a separate list. For one thing, a major, if not the main use, of the method is for iteration, as in 'for keys in d.keys():'. For this, creating and them discarding a separate list is inefficient and, in a sense, silly.
One option is to make .keys be what .iterkeys is today. Another, more recent, is to make .keys return a new iterable dict view object, details not yet worked out. Either way, one would make an independent set or list with set(d.keys()) or list(d.keys)). Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
