While there is nothing inherently masculine about the way in which Google+ operates, we've seen time and time again that the demographic breakdown heavily favors men. Similarly, there's nothing inherently feminine about the using Pinterest, but girls have flocked to the site in higher numbers than boys.
And although there's nothing about certain social sites that exclude one sex or the other, it's abundantly clear that some things about certain social networks are more attractive to men, and some things appeal to women. And the lines are rather clearly drawn.
First off, women are more likely to participate in social media in general. And they hold a commanding lead in two of the most popular networks - Facebook and Twitter. In fact, nearly 2/3 of Twitter users are women (and 58% of Facebook users).
Women also dominate Pinterest with more than four times the users as men.
On the flip side, reddit seems to be the guy's version of Pinterest as they dominate the social aggregator with 84% of the membership.
Another interest fact about the sexes on social media is that there are more men on LinkedIn alone that al off the women on reddit, LinkedIn, and Google+ combined.
Check out the "Battle of the Sexes" in social media infographic below, courtesy of Digital Flash NYC.