The buttons in OS X have gone through a couple of revisions over the years. IMHO, the current look is the best — clean and graceful without getting in the way.
Apple displays graphic buttons on their web site, so even non-Safari users can enjoy their lovely button stylings, but they seem to have fallen behind the times in some places. I think the button on the left is an example of what buttons looked like in Jaguar, and the button on the right matches what I’m seeing in Tiger.
Just a minor observation — I know how hard it can be to keep track of all your image assets.