As passed along by Aaron Gleeman at Hardball Talk, the Padres appear to be interested in signing Carlos Quentin to a contract extension before he hits free agency after the 2012 season.
Why, though, the Padres would want to sign Quentin to an extension is a little curious. Half of his four seasons with the White Sox saw Quentin be worth at or below replacement value (per FanGraphs' WAR) due to his propensity to get hurt and poor defense. Playing the outfield in a stadium as spacious as Petco Park probably won't help Quentin's defensive value, and his offensive numbers may take a hit playing half his games there as well.
That being said, Quentin will come to San Diego with good offensive numbers built up with the White Sox. He hit 107 homers and posted an OPS above .800 in three of the last four seasons -- not great, but well above average. His value, most likely, would be based on his time with the White Sox, not the Padres.
So, in short, signing Quentin to a contract extension would be fairly risky for San Diego -- at least, until they find out exactly what they have.