As always, BitSimple takes security seriously so even our temporary server is 100% dedicated (no VPS or backdoor super admin accounts) and I personally installed the OS and configured the BIOS remotely over IPMI.
I read this paper once
http://fish2.com/ipmi/bp.pdfnot sure I would entirely trust IPMI to be left switched on if I was running a server.
IPMI access is on a private VLAN behind a dedicated hardware firewall. You are right IPMI should never be on a public untrusted connection.