Are there a downsides to hiring someone who graduated from a Women's College?

No, there are no downsides to hiring someone who graduated from a Women's College. Women's colleges are on par with other colleges (simply research the quality of the school as you would any university). As far as the graduates, in addition to a quality education, the women who graduate from these academic environments have had great opportunities for leadership and encouragement in fields that might be considered male dominated at other schools.

There are numerous examples of extraordinary women who have graduated from women's colleges. http://en.wikipedia.org/wiki/List_of_alumnae_of_women's_colleges_in_the_United_States

That said, the number of women's colleges are decreasing as many of the schools have merged their women's colleges into the main university.

This article is worth a quick read to hear a graduate's perspective:
"It’s a place where students dare to defy gender norms. It’s a place where students come to engage in leadership roles that they may not otherwise have had access to."
http://www.forbes.com/sites/rachelhennessey/2013/02/06/whats-in-a-womens-college/

As the ratio of men to women in in co-ed colleges has decreased over the past few decades, the need for all-women's colleges has decreased somewhat. However, it is delusional to think that there would be anything lacking in the education of a woman graduating from an all-woman's college or that entrenched sexism no longer exists at US universities and that some women prefer not to have to deal with that at the college level. Anecdotally, the two women I have known who came from that environment, one a physical chemist and the other a physicist, both were stellar scientists and went on to graduate school and very successful careers. Each had different reasons for attending an all-woman's college, but both said the experience was great and at least to me seemed to be relatively normal. I can't see how there would be a hiring bias based on attending an all-women's college unless you want to count all gender-biased hiring decisions as part of that.

No , I do not think there are any downsides. I started college at an all women's college and later transferred to a coed University for options within my major but I felt as though there were less distractions while I was in the all women's environment and more focus on promoting women's issues. I don't see in the IT field that coming from al all women's college background is an inhibitor to being hired. It is more a question of what your major and experience have to recommend you.

Repeat after me : THERE ARE NO DOWNSIDES. Now that I got that out of my chest, lets get in to it.

As a women myself, I see this kind of questions come up for me all the time. When I take charge, I am called bossy, when a man does it he is brave. When a man wants a manager promotion he has guts, when I want manager promotion, they ask me why? This is called bias and from the way you are asking the question you seem to have gathered some too. This perfectly normal, so don't be alarmed.

Here is an article that talks about gender bias in interviews : https://www.glassdoor.com/employers/blog/9-ways-to-remove-gender-bias-from-interviews/

Here is another article on gender bias : http://theconversation.com/to-achieve-gender-equality-we-must-first-tackle-our-unconscious-biases-92848

Next steps : Please read these articles and google more about gender bias. This way, if there is someone who is biased towards you , you can ask the right questions to deal with it. If you are having the bias, then you would know how to over come it. Good Luck!