UPDATE: Secretary of State Delbert Hosemann rebuked  the Brennan Center, claiming that its recent report  “is purposely inaccurate and is misleading in its statements about Mississippi.” The Brennan Center stands by its research  – “[county offices] are still untested as voting ID issuing offices” – reinforcing the fact that the new law warrants close scrutiny.
Last November, Mississippi voters approved by referendum a voter ID constitutional amendment.  Because the amendment required enacting accompanying legislation, the legislature then passed HB 921,  which Governor Phil Bryant signed into law on May 17, 2012. ALEC  Members Joey Fillingane and Bill Denny were behind these efforts.
We have known for some time that such laws put voting even further out of reach for many vulnerable  populations , and recent analysis confirms  that the Mississippi law could make it virtually impossible for some of these citizens to vote. Secretary of State Delbert Hosemann has asked  state residents to let his office know if they lack ID, and says that they aim to provide free ones. But, that free ID is causing its own problems. Jackson Free Press: 
One of the requirements to get the free voter ID cards is a birth certificate, but in order to receive a certified copy of your birth certificate in Mississippi, you must have a photo ID. Not having the photo ID is why most people need the voter ID in the first place.
Fortunately, we have at least a slight reprieve, as it seems very unlikely that the law will go into effect by November. Hosemann said shortly after Governor Bryant signed the bill that it would need to receive Department of Justice approval by July in order to be implemented in time, and as of July 9, Mississippi has yet to apply. 
For more information, check out The Right to Vote under Attack: The Campaign to Keep Millions of Americans from the Ballot Box , a Right Wing Watch: In Focus  report by PFAW Foundation.