Given my experiences in MMOs playing both genders, I found this article on Geekosystem about men who play female avatars very interesting.
I know that when I play female avatars, I pretty much play me, just with a different set of electronic bits. However, I'm apparently in the minority, as there seem to be an abundance of flirty behavior when men cross genders and play as women.
From my perspective, it's hard to say who is who on some games such as WoW, because when you're standing around waiting for the gates for AV to open you can tend to get bored and jump around.* But given the large increase in the likelihood of certain behavior, I do have to wonder whether it is done consciously or not. I'm skeptical about trying to hold male players' attention, particularly given how skimpily some female toons are dressed**, but if it is a glorified "look at me" just for the hell of it, then I consider that a bit more likely.
And considering how much "attention" my male Blood Elf bank toon got on his run from Sunstrider Isle to Silvermoon, I think it does work both ways.
*Or you could be merely wired from a few Monsters or Red Bulls.
**If you want examples of this in SWTOR, go visit Njessi's excellent blog Hawtpants of the Old Republic for her Fashion Hall of Shame, a collection of really really bad fashion choices.