I find it interesting that so many people on this site were against gays (serving openly) in the military because the military isn't a place for social experimentation and advancing social policy, and yet so many of you think it's a good place for taking chances on (hopefully) reformed felons.
I know the issues aren't directly tied, but I think their is a common thread that underlies them--that the military isn't the place for taking chances just so everyone can get warm fuzzies. I believe that felons are potentially capable of reforming themselves, but I also believe that once you've proven yourselves capable of serious crime, there are certain forums that I don't think are appropriate for testing whether or not they are reformed. I am sure there are some child molesters that change their evil ways, but I'm still not going to hire one to babysit my kids just because I think everyone deserves a second chance.
Military service is too important to risk putting it in the hands of someone who swears--and we hope truthfully so--that he's changed.
That being said, perhaps lesser felonies, as considered on a case by case basis, might be worth overlooking. The chance you take on someone who stole a car when he was 17 is a lot smaller than taking a chance on someone who forcibely raped someone.