spyware implies they're pulling information off your box to use for some nefarious purpose... it's nothing that sinister. They simply cannot sell you a file that you can immeadiately drop into kazaa & share w/ 2000 of your closest friends. remember, we're going legal here. As far as I can tell, the file(?) knows who it's allowed to be played by, and if someone else tries to play it the owner(you) has to authorize it. you can have 3 (sorryI was wrong earlier) people authorized to play your stuff at once. This is the best link I could find you... it's a tutorial on iTunes in general and the music store in particular, and hopefully it'll answer your questions...
http://www.apple.com/support/itunes/tutorial/index.html