I'm uncertain how many people know this, but Starcraft was heavily based on the WH40k universe. Zerg are modeled after Tyranids, Protoss are modeled after Eldar and Terrans are modeled after Terrans. Obviously, the storyline was changed drastically, the Space Marines do not count fanatical devotion to the Emperor as their chief weapon. I find it odd then, that one aspect they chose to keep the same in Starcraft 1 was the exclusion of women in power armor. It seems like common sense that gender and sex would have no impact whatsoever on the capability of a power armor-clad space marine. Even the sexist Heinlein, the first sci-fi writer to make fiction with battlesuits couldn't help but imagine that such technology would lead to an egalitarian armed force where position is based on merit.
Sure, Starcraft 1 did toss us Sarah Kerrigan, arguably one of the coolest super soldiers whose name isn't Samus, but one could easily make the case that she existed only to give us an interesting bad guy later on (ala Arthas), or to flesh out Jim Raynor's character. One would assume that Starcraft 2 would learn from the Warhammer 40k universe (or the Duneiverse for that matter) and introduce an all female army, or a few cool empowered female characters, or just some visible characters that aren't heterosexual white males. What we get instead is a Pioneer Woman in a labcoat in cutscenes, Kerrigan appearing as Queen of blades with extremely vague motives, and in game we finally do get women in power armor...only they can only heal...and if you click on them a bunch they are sexualized much like the dryads from WC3. At the end of the day the only positive depiction of women in the battlefield is the Medivac pilot(s), Banshee pilot(s) and Nova, who appears for one mission in a grey zero suit that can cloak.
I think what bothered me the most in the game was the character of Dr. Ariel Hanson though. She sends out a distress call because her people are under attack from aliens, Raynor shows up and saves the day, then she becomes a member of the crew while her people find a place to settle down. When they finally find a world that seems suitable, she asks Raynor to come live with her (in spite of the fact the two haven't known each other for more than a week, and that for all we know they have never even had one discussion about something other than the Zerg or the Protoss), then she kisses him as he establishes himself all the more a stoic man of action, unwavering in his dedication to the cause. A character introduced, then dismissed, solely to establish character traits of a male lead. Instead of women in refrigerators I guess it's women running from Zerg/Protoss in the land of SC2.
The Whole Ariel Hanson story arc felt tacked on, by the by. Not saying there weren't some fun and creative missions there but if I had to pick any part of the campaign where it felt like they wedged it in to make the campaign longer to be better able to justify breaking the game up into three parts, it would definitely be that part of the campaign.
As far as Nova, she shows up, is pretty cool as far as doing the exact same thing Kerrigan did in the first game (minus being abducted by the zerg) and then leaves after one mission. I don't know what else to say, except I wish they made Starcraft: Ghost.
There is also the Kate Lockwell, who is constantly having everything she says dismissed by her Glenn Beck-ish co-anchor. She is a fairly entertaining character, but only appears in optional cut-scenes. This character really doesn't stand out too much, likely because of how little impact the news team has on the story proper.
In game we have the Medic unit the Medivac unit and the Banshee unit, all female gendered. As mentioned previously, the Medic unit makes sexually suggestive comments as the "joke", in a manner similar to the dryad. The Medivac unit just makes some Airplane! jokes, which is fine for those of us over 25. The Banshee unit is actually pretty cool, has a few "banshee" related jokes. At the end of the day, if you are male in the SC universe you can be a: space marine; combat pilot; transport pilot; tank operator; battlesuit operator; HUGE battlesuit operator; starship captain; medic; scientist; Ghost; Spector or TV Anchorperson. If you're a Woman you can be either a: Doctor; Ghost; Banshee Pilot; Merc (there is one I forgot to mention), or an Anchorperson. I suppose also Queen of Blades but that position is occupied.
I'm going to close by saying that in spite of the few women that did appear, Kerrigan is the only one who really impacts the story, and even at that her motives are unclear. In DOW2, although there was only one visible female gendered character, she saved several worlds through actions that put her own life in danger. Given the impact Jayna had in WC3, I'm somewhat surprised that female gendered characters are thrown by the wayside in SC2. Perhaps this will change in future chapters?
PS: Needless to say, LGBT are completely invisible in starcraft 2. There are no conversations between 2 women and there sure as hell are no conversations between 2 women which does not relate to a man.
PPS: I didn't mean invisible as in they have cloaking fields. Although perhaps that is possible.