http://jjcm.org/css3-buttons/ Here's a demo page. I agree though, ridiculous that it didn't include one.

edit - tried them in IE6/7, they don't degrade that gracefully. They exist and work fine as buttons, but visually it's hard to tell that they are. If you use this I'd recommend adding a :hover on the span's background color as well just so a user knows to click the thing.