According to the pilot, following the preflight inspection, he entered the airplane, proceeded through the pre-engine start checklist, and set the parking brake. After several failed attempts to start the engine, the pilot increased the power lever setting before another start attempt. The engine subsequently started, and the airplane "abruptly launched forward," and "skidded through the parking [brake]" toward another airplane parked 150 feet directly ahead. The pilot immediately applied right rudder, which turned his airplane to the right; however the right wing struck the propeller and left wing of the parked airplane, resulting in substantial damage. The pilot subsequently exited his airplane uneventfully after it skidded to a stop. A witness reported hearing the airplane's engine start and described that it sounded as if the airplane was "ready to take off." A photograph revealed tire skid marks leading to and beyond the parked airplane.