As covered in the Columbus Dispatch here and the Cleveland Plain Dealer here, Jim Petro (R-Rocky River) has dropped County Commissioner Phil Heimlich (R-Cincinnati) as running mate. Heimlich will run for reelection to his old seat, not Lieutenant Governor. (By the way, Heimlich's father was the inventor of the famous life-saving maneuver.)
Additional details after the flip.
This is seen as a significant stumble for Petro, who has already had to deal with losing his campaign manager Matt Cox last September and the allegation in December by an attorney that one of Petro's fund-raisers offered him lucrative legal assignemnts for the state in return for a campaign contribution.
Among the other major party candidates, only Bryan Flannery has announced a running mate: TV football commentator and former NFL player Frank Stams. There has been talk that Ted Strickland may pick Cuyahoga County Commissioner Peter Lawson Jones, who is African-American and a northern Ohioan.