--- powernowd_org	2008-07-14 04:49:20.000000000 +0200
+++ powernowd	2008-07-05 03:38:09.000000000 +0200
@@ -7,7 +7,7 @@
 
 start() {
 	ebegin "Starting powernowd"
-	/usr/sbin/powernowd -q ${POWERNOWD_OPTS}
+	run-jail powernowd /usr/sbin/powernowd -q ${POWERNOWD_OPTS}
 	eend $?
 }

;
; RSBAC JAIL definition for powernowd
; 20080507
;
; Tested by igraltist
;
 
""
"0.0.0.0"
(allow-dev-read
 allow-dev-write)
()
(sysfs)
(sysfs)

This is execute now:
rsbac_jail  -d -D -G  sysfs -M  sysfs /usr/sbin/powernowd  -q