An MSNBC article asks this question and provides a grim update on President Obama's use (or, rather, non-use) of his power to pardon and commute offenders:
President Barack Obama is on track to be one of the least forgiving of presidents in U.S. history — as measured by his use of presidential pardon powers, according to a political science professor who blogs about clemency exercised by presidents and governors. ...
As president, Obama has pardoned 23 people, including one commuted sentence, in his first 40 months in office. Barring a dramatic flurry of clemency from the White House in the coming eight months, Obama will be among the bottom two or three presidents for granting pardons in his first term, Ruckman said. That puts him in the running with Presidents George Washington, John Adams and James Garfield, who was assassinated after serving less than seven months.
While campaigning for office, Obama was critical of the mandatory minimum penalties for drugs, especially those that specified much heavier sentences for those using crack cocaine than to the ones associated with more expensive powder cocaine.
Mandatory minimums, which emerged in the 1980s, are partially responsible for swelling federal prison populations — to 218,261 on the week of May 3, compared to 24,363 in 1980, according to government documents.
In April 2010, the president signed into law the Fair Sentencing Act, which aimed to even out the mandatory minimums, which critics say are discriminatory to African Americans.
But Obama did not — as some expected or hoped — go on to throw open the doors for large numbers of people incarcerated under the old mandatory sentences. ...
In a statement then from the nonprofit Families Against Mandatory Minimums, president Julie Stewart urged Obama "to continue exercising his clemency power and grant more commutations to the many deserving federal prisoners, like Eugenia, who have paid a hefty price for their mistakes and deserve a second chance."