Hello Jason,
do pistachio have support for ARM processor (particular ARM9)
To answer your question, Pistachio can be used on x86 CPUs (and PowerPC), not on ARM (anymore). In general, you can find such information on the official pistachio website:
http://www.l4ka.org/projects/pistachio/
or
http://www.google.com/search?q=l4+pistachio
the first hit ;-)
regards Stefan
PS: At the bottom of that page you can find a link to the official Pistachio mailing-list.