According to the pilot of tandem cockpit, tailwheel-equipped Piper airplane, which he was operating from the rear seat, while taxiing to the runway his forward visibility was diminished by his airplane's nose, requiring the use of "S" turns in order to clear the area in front of the airplane. He reported that a Cessna airplane was in front of his airplane, and taxiing to the runway as well. He remarked that he and the Cessna were holding on the taxiway momentarily in order to monitor and give way to arriving and departing traffic. He reported that the Cessna moved forward, and he followed, but while entering the "S" turn, he lost sight of the Cessna. He remarked that he abruptly applied the right brake in order to avoid a collision, and his left wing impacted the Cessna's rudder. The pilot of the Cessna reported that during his taxi to the runway, his airplane was struck from behind by the Piper airplane. Both pilots shut down their airplanes, assessed the damage and exchanged information. The Cessna sustained substantial damage to the rudder, while the Piper sustained minor damage to the left wing. Both pilots reported that there were no mechanical failures or anomalies prior to or during the flight that would have prevented normal operation.