If you have the time to sift through the many results, just Google it (if you haven’t already here is one link with some interesting answers http://answers.yahoo.com/question/index?qid=20080202182627AAlc69V), you will be surprised at what you find, however I do know there are different types of discharge. It could dishonorable or less than honorable, not sure which they would use. But either one causes you to lose benefits and effects your resume. Another thing, if he was an enlisted man and involved with an officer, the officer would more than likely be busted down for fraternization.
One true anecdote I can share came from my sister (a lesbian) who served in the Army for 24 years. She retired a Command Sargent Major which is the highest rank an enlisted person can achieve. Her MOS was Army Intelligence (talk about an oxymoron!) and they were tasked with among other things investigating soldiers for various reasons by doing forensic tests on their computers. Her boss knew she was gay, he and his wife attended parties at her house (she shared with her lover) and it was never a problem. She always told me that the brass used the DADT on people who were total fuck-ups and it was the only way to get rid of them. I have no evidence of this, it is just anecdotal, but it came from her.