With previous versions of iTunes on the Mac, you could always get the miniplayer by clicking the green + symbol meant to maximize applications. As of iTunes 9, that shortcut no longer works. Instead it maximizes the iTunes window. Doh!

Never fear, there is still an easy shortcut to get the miniplayer in iTunes 9. Before you click on the green + symbol hold down the Alt key on your keyboard (the Option key on some keyboards). If you do this, you'll get the miniplayer instead of a maximized iTunes window.