A recent Gallup poll (I've always wanted to say that) indicates that acceptance of "Homosexual Relations" has surpassed 50% in the US. Acceptance by men and Catholics appears to be driving the shift.
Since May 2006 there's been a 14% increase (to 53% of respondents) in acceptance of "Homosexual Relations" among men of all ages. For men under 50 that number increases to 20%. Interestingly there's been only a 2% increase among women. 51% of women say they find Gay/Lesbian relations "morally acceptable".
Among Catholics acceptance is up 16% in the same time frame to 62%.
See
here for more information including more fun infographics as well as full methodology.