UPDATE: The Human Rights Campaign says she definitely was with a different Exodus:
During the announcement, President Bush referenced Miers' affiliation with Exodus Ministry. This is not the so called "ex-gay" group, but is "a non-denominational Christian organization established to assist ex-offenders and their families become productive members of society by meeting both their spiritual and physical needs." (http://www.exodusministriesinc.com/)More here, and here.