I just checked the 2009 Watchtower Library. There has been no new information on this since the 1979 that said that being a member of the YMCA would be interfaith. w79 1/1 p31 says, in part:
"In joing the YMCA as a member a person accepts or endorses the general objectives and principles of the organization. He is not simply paying for something he receives, such as when buying things being sold to the public at a store. (Compare 1 Corinthians 8:10; 10:25). Nor is his membership merely an entry pass, as when a person buys a theatre ticket. Membership means that one has become an integral part of this organization founded with definite religious objectives, including the promotion of interfaith. Hence, for one of Jehovah's Witnesses to become a member of such a so-called "Christian" association would amount to apostasy."