Apple has released Open Firmware Password 1.0.2. The release is firmware-protection software for Mac OS X 10.1 or later on Macs with Firmware update 4.1.7 or later.
The software enables security features in Open Firmware that enhances security access to Macs. The firmware prevents Macs from being started up from a volume other than the volume selected as the startup disk
Once the security-protection software has been enabled, start-up is not possible through other devices, such as external FireWire disks, CD-ROM drives, or a internal disk-partition.
The software is free to download from Apple's Web site, or is available through the Software Updates feature in Mac OS X.