in reply to perl distribution for hp-ux
ppm is an ActiveState thing.
Unixes in general have a more compatible environment for programs like perl to compile, so a seperate vendor like ActiveState is not required to get perl up and running on the normal UNIX platform. Thus each vendor has their own package.
HP-UX is not the only UNIX flavor in existance. Other vendors supply much more 'clothed' perl packages.
Also note that I think ActiveState is really cool to have made perl available to the windows audience and applaud their efforts. The ppm package is well liked by the folks here who use it to install modules.