This may be an off the wall question but is there anyway in Solaris to snag the serial number of a Sun box? I'm not sure if you can do this but it would save me a long drive to the data center to get the serial number to renew support...
I've just tried "eeprom", but nothing obvious.
Try downloading and using sneep (SUNWsneep) if it is available to you.
Sneep can help, and you can also program it into the OEM Banner field (which is normally unused) in eeprom when you're at the openboot prompt.
Often the hostid is the last four bytes of the ethernet MAC address.
on some of the new SUN stuff you can get the serial number with sneep.
on the older SUN stuff you must go onsite and use your eye-balls to colect the serial number of the back of the box.
I must have seen at least half a dozen Solaris serial number threads. The search engine would probably find them in case anyone is interested. 
Don't know if hostid would be any helpful.
if YOU (or anyone else) didn't enter the serial number with sneep or into the sun-explorer, you have to travel the way to the datacenter.