This is a demonstration of the obpbanner command for Solaris.

Here is banner from the OBP (OpenBoot PROM),

   ok banner
   Sun Ultra 5/10 UPA/PCI (UltraSPARC-IIi 333MHz), Keyboard Present
   OBP 3.15.2 1998/11/10 10:35, 768 MB memory installed, Serial #10929453.
   Ethernet address 08:00:20:a6:c5:2d, Host ID: 80a6c52d.


Now using obpbanner from Solaris,

   # obpbanner 
   Sun Ultra 5/10 UPA/PCI (UltraSPARC-IIi 333MHz), Keyboard Present
   OBP 3.15, 768 MB (50 ns) memory installed, Serial #10929453.
   Ethernet address 08:00:20:a6:c5:2d, Host ID: 80a6c52d.

Of particular interest in the serial number, which is not easily 
obtainable from Solaris. Note - this isn't the same serial number as the
sticker has on the box.