Most of the current generation hp ProLiant servers (really all
except the very low cost ones) have an embedded management chip,
Integrated Lights Out (iLO).
The cool thing is you can drive all the iLO's operations (power on/off
server, user admin, etc) by sending XML across SSL to it's NIC. HP
has recently put out some sample perl to show you exactly how to do
Be sure to have the perl modules IO::Socket::SSL
Check it out: HP Lights-Out Perl Scripting Sample