Java.sun.com has published an article by Daniel Steinberg that explains how to use Java command line options to make a Java application will feel more like a native Mac OS X application.
Despite its pretty face, Mac OS X is built on top of BSD UNIX and comes complete with J2SE and Java Web Start installed. Developers can pop open a Terminal window and find that their favorite geek tools like vi, emacs, and the Java command line tools are already installed. Check a checkbox and you've enabled the built in Apache server. The Mac is a great platform for Java developers with a wide array of commercial, free, and open source development tools available. Whether or not you develop on a Mac, take the time to make a small number of changes to your application so that you provide a Mac-like experience for the millions of potential customers who already use Mac OS X. These end users don't care what language your application is written in, they just want a double-clickable application that is attractive and easy to use.