For some reason sun wanted to make the hostname in solaris as difficult as possible to change. For reference (my own and others) here is the list of files that have to be modified to change the hostname in solaris.
/etc/hosts
/etc/nodename
/etc/hostname.*
/etc/net/ticlts/hosts
/etc/net/ticots/hosts
/etc/net/ticotsord/hosts
/etc/inet/ipnodes
After which you should reboot to test out the new hostname.