The Pew Forum on Religion and Public Life has an interesting synopsis on where the presidential candidates stand on the death penalty, including any key votes they've taken on the issue: http://pewforum.org/religion08/compare.php?Issue=Death_Penalty
There's also some analysis of public opinion polls on the issue: "For most religious traditions, there are only slight differences in opinion on this issue between those who attend religious services at least once a week and those who attend less often. The one exception is white non-Hispanic Catholics. Among this group, those who attend services more frequently actually take a more liberal view on the death penalty: 39% of white non-Hispanic Catholics who attend religious services at least once a week oppose the death penalty, compared with only 22% of those who attend less often." http://pewforum.org/docs/?DocID=272
