Whether it's a book, a film or a game, a sure sign of something being an important work is when someone starts reading hidden subtexts into it. Having been an English Literature student and subjected to this or that tutor's crackpot theories about this or that novel on a regular basis, I unfortunately have a very thin tolerance these days for seeking underlying meanings that the creator probably never intented to be there. So personally, I'm not quite buying the argument in this interesting, funny (and OMGspoilerz) analysis by Bonnie over at Heroine Sheik of how Portal could be a tale of lesbianism, but you may. It's certainly a fine read, and it makes me happy that a game is inspiring this kind of thoughtful, if wry, critique.
But in a world of women, this gun doesn’t shoot bullets. It shoots orifices. Openings. Fine, vaginas. Vaginas you, a female character, have to enter/exit to solve puzzles. I don’t say this often, and almost never with so much support and enthusiasm, but that is so gay.
- Bonnie Ruberg
Whether it's gay or not, as a game with an all-girl cast (WCC aside), at least one female lead developer (in Kim Swift), and minimal emphasis on the traditional FPS pursuits of destruction and violence, there's certainly much to be said about Portal and gender. It doesn't present the potentially oppressively masculine scenario that us meatheaded boys usually play, and that's probably why we're hearing sporadic tales of "my girlfriend plays Portal" and the like. Though I suspect that, really, it's much more to do with Portal actually innovating rather than sticking doggedly to the genre's guns. So to speak.
Edit - any game can, of course, have its gender appeal entirely reversed with just a few simple tweaks (with thanks to Tom from ThinkingGames for the link):