Interesting report from the Brennan Center for Justice on problems with voter ID laws. See also an articles on this report at Colorlines: Study Links "Racial Resentment" and Voter ID Support.
From the report download page: Ten states now have unprecedented restrictive voter ID laws. Alabama, Georgia, Indiana, Kansas, Mississippi, Pennsylvania, South Carolina, Tennessee, Texas, and Wisconsin all require citizens to produce specific types of government-issued photo identification before they can cast a vote that will count. Legal precedent requires these states to provide free photo ID to eligible voters who do not have one. Unfortunately, these free IDs are not equally accessible to all voters. This report is the first comprehensive assessment of the difficulties that eligible voters face in obtaining free photo ID.