Now no longer the center ring for the traveling Democratic presidential nomination circus, Pennsylvania's inventive political community has discovered a new favorite political parlor game to while away the brisk springtime evenings: will Chris Matthews, the irrepressible host of MSNBC's Hardball, step down from his pundits perch to run for the US Senate against Arlen Specter in 2010? To a remarkable degree, speculation abounds over this possibility in the Keystone State. The indications that Matthews will run are abundant. His MSNBC contract runs out next summer, and both he and the network show signs they might be ready for a...