The main difference between PhunkyBB and other forum software packages is its use of XSL as its template language. There aren't too many web applications which use XSL yet, even though in my opinion its the best choice, and I hope that will change over time.
By using XSL, PhunkyBB is able to run on several different platforms, not only in terms of operating system, but also programming language. At this time, its only tested and used on PHP, but some test runs have been done on perl, python, TCL, and ruby. Cool, huh?
It should be obvious from the interface that PhunkyBB was greatly inspired by punbb, but almost none of the original code from punbb is used anymore. I hope to restore some of the functionality which was removed during the rebuild, but in the meantime I'm working on just making the forums system work as solid as it can.