This script by Brendan Gregg lets one run a command in all zones (except the global zone).
Obviously it only works from the global zone 
#!/usr/bin/sh
# zonerun - run a command on all non global zones. Solaris 10.
# 10-Mar-2005, ver 0.80
# USAGE: zonerun [-v] command
# eg,
# zonerun uname -a
# zonerun -v uptime
# Standard Disclaimer: This is freeware, use at your own risk.
# 10-Mar-2005 Brendan Gregg Created this.
PATH=/usr/bin:/usr/sbin
verbose=0
if [ "$1" = "-v" ]; then
shift; verbose=1
fi
for zone in `zoneadm list`
do
if [ "$zone" = "global" ]; then continue; fi
if [ $verbose -eq 1 ]; then
echo $zone,
zlogin -S $zone "$*" | sed 's/^/ /'
else
zlogin -S $zone "$*"
fi
done
Found at http://www.armoredservers.com/support/Zones/zonerun.