Contrary to the claims of some conservatives, gays can and do serve in the military. This video highlights the story of a combat medic at Fort Hood, Texas, one of the major troop installations in the United States. Warning: long video (13 minutes).
Sergeant Darren Manzella served as a combat medic, and his chain of command investigated the claim that he was gay. Manzella provided pictures and video of him with his boyfriend, but found "no evidence of homosexuality."
The story makes clear that Manzella gave them plenty evidence of homosexuality, but it didn't make any sense to get rid of a good soldier in a critical field when he wanted to continue serving and there was a war going on.
The British and Israeli armed forces allow gays to serve openly and still have first-rate combat units. When Admiral Mullen, Chairman of the Joint Chiefs of Staff, says it is time to repeal DADT and believes that we can do so without compromising readiness, objections based on domestic politics, and not on military grounds, lose a lot of credibility.