If you aren't already familiar with Veerle's Blog, you should check it out. Veerle lives in Belgium and has a fantastic blog that covers Illustrator among other applications. Veerle, a strong supporter of CSS, is also a talented designer (far more talented than yours truly I should add).
Recently, Veerle posted a step-by-step tutorial on how to create those cool-looking buttons that Apple is now using in Leopard and on their website. To take Veerle's excellent concept one step further, I've recorded a podcast which shows how to create those same buttons using Illustrator's Graphic Styles and the Convert to Shape effect.
You'll find my podcast over at Terry White's most excellent Adobe Creative Suite Podcast site. Enjoy!