My guess about the piano: someone setting up for a student film. "It'll be safe till tomorrow. *Nobody* comes here."

Speaking of things left in the woods: did you read about the meat (http://www.boston.com/news/local/massachusetts/articles/2008/11/21/mystery_meat_has_framingham_all_abuzz/)? [More meat (http://www.metrowestdailynews.com/news/x2067099669/More-meat-found-in-Centre-common-being-tested)]