This feature is new in the Solaris Express 11/04 release.
Intelligent Platform Management Interface (IPMI) is an industry standard that supports some aspects of “lights-out” server management. Most x86-based servers have a built-in management controller (bmc) that enables systems to be remotely managed. For example, a system can be powered on and off, and temperatures and voltages can be measured remotely.
IPMI is open source software. Documentation is available on the web at http://openipmi.sourceforge.net/.