I don't think anyone is trying to deny that Curie gets a little more attention in the school curriculum and the popular mind just because she's a woman, but I think the point asnyder was making is that she at least has the distinction of being a great scientist, unlike George Washington Carver who (and I had to look him up, since having not been educated in the US I'd never really heard of this guy) doesn't seem to be in that category.
Oh, and be careful with statements like "almost no one reading this knows who the hell Onsager and Landau are". There's a surprisingly large number of physicists reading this board.
We aren't talking about the users of this board, we are talking about the average American who went through the public education system. 99.9% of them have heard of George Washington Carver, but not of Onsager and Landau.
Your original interpretation was right. Perhaps I underestimated the number of physicists hanging out here. (I hope so! It would be cool to think people here know who these guys are.) In any case, the original point remains: even on Hacker News, Marie Curie is far better-known than Lev Landau, and it's not because she was the greater scientist.
Oh, and be careful with statements like "almost no one reading this knows who the hell Onsager and Landau are". There's a surprisingly large number of physicists reading this board.