If you aren't aware of it, there is a great (and FREE) cross platform installer done as the reference implementation of JSR 38 (Application Installation API Specification)
I just checked it out and it is very similar to the (potentially expensive) Install Anywhere product. Which makes sense since Zero G, maker of Install Anywhere, is on the expert group.
If you need a full featured installer for your Java (or Native) app this looks like a good package. Currently support Windows, Solaris, Linux - No Macintosh support, but it is extensible so perhaps that can be added easily.
Check it out at:http://www.openinstallation.org/