What if you have a x86 system with lots of memory and you want to reboot it? It will probably take minutes before your system starts booting. What if you could bypass BIOS and POST testing and go directly to bootloader? Such a nice feature has been just integrated into Open Solaris build 100. See PSARC 2008/382 for more details.
A new "-f" flag has been introduced to the "reboot" command which allows a faster reboot that bypasses the BIOS and grub.