As Bradley #Manning becomes Chelsea (http://bbc.in/16Qg50L)the BBC style guide explains what to say now: http://www.bbc.co.uk/academy/collegeofjournalism/how-to/news-style-guide/t
Do not refer to ‘transsexuals’, in the same way we would not talk about ‘gays’ or ‘blacks’. Transsexual people who have completed surgery to become a member of the opposite sex should be referred to as the gender they have become. Pre-operative transsexual people should be described as they wish. If their wishes are not known, and it is not possible to find out, take an informed view based on knowledge of the individual’s lifestyle. For example, it is reasonable to assume that a woman living as a man would wish to be referred to as ‘he’ rather than ‘she’.