I am open everywhere I go, I have several stickers on my car, as well as a "dyke" haircut, but there are a lot of conservatives in the town I live in and my wedding ring (very pretty) draws quite a few comments. I usually just correct someone when they say husband and keep talking. I am honest with anyone who asks, but I don't believe that sharing personal information with a patient is a good idea, unless you feel that they would not make a big deal about it.
The divorce rate that someone pointed out is less than 50% and is more like 40%. I personally do not want to replicate a heterosexual marriage, but I want my wife to easily get my healthcare coverage, and I really want our kids to be adopted by both of us and that is not allowed in Michigan. Theres roughly 1100 rights you lose being married to someone to the same-sex and that affects nearly every aspect of life. I agree with the idea of government butting out of gay marriage whole-heartedly.
Back to the subject, I would like to work in OB/Post partum and If the lady giving birth was someone with a closed mind and knew I was gay, I could see that getting ugly. So basically keeping it to yourself,and sharing just with co-workers you have known awhile is probably safest.