Tales from the Tigerfort

I've recently read various discussions of the Bechdel test. For those who've not encountered it, the test was originally proposed in "Dykes to watch out for", and a film passes the test if it meets the following conditions:

1) it contains at least two female characters
2) who talk to each other
3) about something other than men. (One reasonable extension also excludes marriage, babies, etc, as sole topics of conversation.)

Most Hollywood output still fails this test, and a large number of books do too.

But I've not yet seen a discussion that considers the way in which the rule potentially falls down when faced with some of science fiction's most interesting - and thoughtful - studies of gender issues. (Fundamentally, the rule is a good one, and it's notable that I can't think of a single major film that includes any of the issues I'm about to note, never mind gives them serious consideration.) I should probably say before I start that ( the text under the cut is quite long, and potentially contains minor spoilers for a couple of books )