When running under MacOS X in GUI mode, the application menu is named after the main class name "net.sf.dvorcode.Main". The Jar should be packaged such that MacOS gives it a proper name, as explained in Apple's Java developer guidelines. An Icon would be nice too.
The limiting factor here is that, while Apple do provide free developer tools for building Java applications (Xcode and JarBuilder), these are only available for the Macintosh, and I don't have ready access to one (I can borrow a friend's Mac to test on, maybe).
The good news is, It should be possible to package the Jar without having a Macintosh with Xcode or JarBuilder installed. I found some pointers:
http://www.google.com.au/search?q=mac+jar+bundler+linux&hl=en