well, even if you look at the *cough* ton *cough* of java apps that are shipped out there many you will find still ship separate installers for each platform. This is because they either a) require a specific vendors or version of java vm, b) run native code anyways to work with native os functions, or c) are written in such a way that they must be tweaked to run on each platform. I see no difference packaging up 3 PAR bundles (solaris, windows, linux) and offering them based on the OS that you will be running on.
