Of course, nothing is certain just yet, but this is what I read.
"The swelling in Mark Prior's elbow has receded enough for the Cubs to believe Prior can return by the All-Star break in mid-July. "I'm hoping before," manager Dusty Baker told the Chicago Tribune. "As soon as the swelling has subsided, he can start throwing again and get his arm strength back. It just depends. Usually when there's swelling, that last bit of swelling is tough to get out. Trainer Mark O'Neal said the team hopes to have Prior back before the break, refused to set a timetable until he knows how Prior reacts to throwing again. The Cubs won't put pressure on Prior to make a quick return, so as to avoid aggravating the situation."