you can post the sheet music on the net freely
Well, you can post sheet music that you wrote up yourself on the net freely. Note that for any sheet music you buy at the store, even of works that are hundreds of years out of copyright, generally still have the actual typesetting under copyright (and often a big "NO COPYING" tag on every page). (Most sheet music these days is copyright to companies like Warner Brothers.)
While admittedly this is not unreasonable (music typesetting is hard!), it always sucked for the student orchestras and choirs without much of a budget I was in...
