I am a recent graduate and on my campus it wasn't uncommon to see people who were gay being members of Greek organizations. Having said that, even on my liberal campus it was "unofficially" known which houses would be more accepting and which would be less.
I don't know what kinds of schools you're looking at, and I don't think that you should bring up your sexuality directly during recruitment. That could be quite awkward just because it's not generally seen as an appropriate topic to talk about.
However, if you want to say something indirectly, perhaps mentioning being involved with the LGBTQ group on campus would get the point across without being too forward. I know on my campus they had a lot of activities, so it could be as simple as saying you plan to get involved with a sub-section of the organization (or that you are, if the recruitment is in the Spring and you're involved already).
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Alpha Omicron Pi Friends as the years go by
Loving sisters are we
Loyal, forever, Alpha to thee
Something to think about... While some may be accepting and cool, be prepared for women who say, " if we take her, we'll become known as the lesbian sorority." I think this would be what one might hear a lot vs. actual acceptance. This of course differs depending on your school and size of chapters, but just some food for thought.
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Be a leader; Be Yourself; Be DPhiE - Esse Quam Videri
I think it's better to be cut from a chapter like that during recruitment than to join and then have someone say that when they find out more about who she is later. No one should have to hide important parts of who they are to be part of a Greek organization. I can't even imagine how horrible it is to feel like one has to hide parts of him/herself in order to be a member of something, and I know I would rather not join than hide who I am.
__________________
Alpha Omicron Pi Friends as the years go by
Loving sisters are we
Loyal, forever, Alpha to thee