People that say that serving with openly gay people hurts morale or troop cohesion usually didn't serve. Honestly, being a volunteer only service, we need as many good troops as we can get.
Well, I did serve, and I will say it hurts unit cohesion and morale, especially in front-line units.
Why, you ask? I'll give it to you in a very simple phrase: "mission focus". For the record, I had little tolerance for those people who were straight who let their sexuality (I ****ed X women last weekend!) override their focus on the task at hand.
This isn't a question of being a soldier, sailor, Marine, or airman FIRST, gay (or straight) second. When one allows their sexuality to override and define them more than being part of the unit, the whole unit suffers.
Bottom line--if you're gay or whatever (and I knew some folks who were), whoop-de-****in-do. When it gets to the point that your "right" to suck dick is more important that killing the bad guys and breaking shit, hit the ****in road. There are lots of other standards which need to be met to serve as well. Drugs, physical fitness, moral character, all are important--so why is it we're changing the requirements? Oh, wait a second--it's not about gays wanting equal treatment, now is it? They DO want "special treatment" after all, don't they?