From Cincinnati.com and John Fay:

The Reds announced a three-year contract extension with left-hander Sean Marshall. It takes him through 2015 with the Reds. I don’t have the money figure yet.

Walt Jocketty said that Marshall could slide into the closer’s role eventually.

Will update, when we have more info.

UPDATE: Ken Rosenthal is saying on Twitter that the deal is for $16.5 and includes incentives for both starting or relieving.