The chaplain is however "not required to participate in or officiate any private ceremony if doing so be in variance with the tenets of his or her religion or personal beliefs."
The Department of Defense memo also said that a military chaplain's participation in a private ceremony "does not constitute an endorsement of the ceremony by the DoD."
somehow I feel like there won't be very many of these ceremonies once the initial "omg we CAN?!?" phase dies down.