Couldn't find a change log.
That's at least 5 years old - I downloaded 1.14beta2 on May 4th 2006.
My bad. I saw it listed an an update from Portable Freeware, maybe it's just that someone has made it portable.
It's possible to run Burrrn by simply extracting the contents of the installer (e.g. using 7-zip) to a folder on your portable drive, so a PortableApp version isn't really necessary.