She's not. She was dating Flash recently (still is, if memory serves), and I never remember her being anything other than straight.
Apollo/MN'er are the only ones I read much (Khell mentioned them). But they actually have personalities (especially MN'er) so it's cool. And they actually write about others coming to terms with them (like Kev, for example, who is more than a little homophobic) so it's a bit more intelligent than some.