Yes, Don't Ask, Don't Tell is analogous to past bans on blacks and women in the military as, much like black soldiers and female soldiers, gays are just as capable as their straight counterparts. Being gay does not suddenly make one ill fit for duty, thus banning them is as asinine as banning blacks and women.
There is gay an argument by analogy that discrimination that they faced is somehow similar to type that blacks and even woman faced. This is a terrible argument. The severity and harshness of both written and unwritten discriminatory policies against blacks than any that was leveled against gays. If it were not for the advancement that blacks made in the armed forces, gays and women in the military would not be able to enjoy many of the opportunities that they currently enjoy.