According to John Fay:

GOODYEAR, Ariz. The minor leaguers reported to camp today. Among them was Mark Prior.

Yes, that Mark Prior.

Prior, a 32-year-old right-hander, has not pitched in the majors since 2006 because of shoulder problems. Hes made several comeback attempts since.

He called me and said asked for a chance, Reds manager Dusty Baker said. I talked to Walt (Jocketty). (Prior) says he feels good. He feels like he has some unfinished business.