To set an IP address permanently in Solaris

just edit two files
#vi /etc/hostname.hme0
change the ip address as required in this file
#vi /etc/netmasks
change the netmask as required in this file

UPDATE: It seems that Solaris 10 now checks the /etc/inet/ipnodes file first before the /etc/hosts file to set the IP. So, if the IP is currently set in /etc/inet/ipnodes, you will have to change it there as well.

* IP -> /etc/hosts
* Netmask -> /etc/netmasks
* Gateway -> /etc/defaultrouter
* IP (again) -> /etc/inet/ipnodes (This is new in Solaris 10)
* DNS Servers -> /etc/resolv.conf