Hi stew-b. I've never heard of this "play to" feature but I'm guessing it's based on DLNA. With DLNA you can select your N900 media files from the DLNA certified TV so it's more "play from" than "play to" but it still achieves the same thing. You can set your N900 as a DLNA server here
http://talk.maemo.org/showthread.php?t=71597