Need iTunes on your website? There's an API for that.
Jokes aside, they might have an API, I'm not sure. If not, you can use the HTML5 <audio> element (with an appropriate fallback for IE8 and below) and just add the button for iTunes. I, personally would use the <audio> element with the link and conditional comments for IE 8 and below just to put a "check me out on iTunes" or whatever link in its place.