The Deacon's Bench has an article on the subject here, including links to an article in the New York Times and the Bishop's letter.
I was disappointed but not surprised to read that a professor at my alma mater--in fact, one of the professors who taught me during my years there--a Roman Catholic Sister, no less--is spearheading a campaign to remind local voters that racism is a sin and that they should not be afraid of voting for Barack Obama. In fact, she is a member of the Catholic advisory Committee for Obama's campaign.
Maybe she should listen to her bishop:
“Being ‘right’ on taxes, education, health care, immigration and the economy fails to make up for the error of disregarding the value of a human life,” the bishop wrote. “It is a tragic irony that ‘pro-choice’ candidates have come to support homicide — the gravest injustice a society can tolerate — in the name of ‘social justice.’ ”