The Pew Forum offers something of note — voter composition by religious affiliation (according to exit polls).
Romney won among all religious communities except Hispanic Catholics, Black Protestants, and “other [non-Jewish/Christian] faiths.” There’s a confirmation of demographic swing against the GOP there, which isn’t surprising. More interesting to me is that the Evangelicals turned out for Romney (79% vs. 20% for Obama) in greater numbers than in 2008 (73% vs. 26%) and 2004. This would seem to suggest that there was no Evangelical anti-Mormon problem for Romney, at least in the composition of the electorate. White Christians can vote for a Mormon.