Well, actually no. They still have the same brain they left with, but twin Mars rovers Spirit and Opportunity get new software to boost their IQ…

NASA’s twin Mars rovers, nearing the third anniversary of their landings, are getting smarter as they get older.

The unexpected longevity of Spirit and Opportunity is giving the space agency a chance to field-test on Mars some new capabilities useful both to these missions and future rovers. Spirit will begin its fourth year on Mars on Jan. 3 (PST); Opportunity on Jan. 24. In addition to their continuing scientific observations, they are now testing four new skills included in revised flight software uploaded to their onboard computers.

Source: Red Orbit