Our mystifying raccoon situation has changed a bit. The raccoon still shows up every night, and he still scratches the same corner of the house; however, he has gained some company.
The other night, I was on my computer (as always), and I heard the raccoon’s inexplicable scratching (as always). But just a few moments later, there was a new sound: the sound of conflict. At first I thought Rosie O’Donnell and Elisabeth Hasselbeck had brought their conflict to our back yard, but when I turned on the light and looked out the window, I discovered the truth. It seems a second raccoon was lured by the oddly addictive properties of the southwest corner of our house, and the first raccoon did not take kindly to that incursion.  My presence put a damper on their fight, but it may not be the last one.
Further bulletins as events warrant.