Apple has updated the Mac OS X security tool Open Firmware Password to version 1.0.2. This firmware application addresses the problem of physical security where someone with a bootable CD or other media can gain access to your system. The update includes minor improvements. From Apple:
The Open Firmware Password application allows you to enable security features in Open Firmware. You can use it to prevent others from starting your computer using a CD or other disk with an operating system on it. You can use Firmware password protection to enhance access security to your computer.
When you set a Firmware password, it prevents others from starting up the computer from a volume other than the one you have chosen as the startup disk (chosen in the Startup Disk preference panel within the System Preferences.) Once security is enabled, you cannot startup from other devices such as an external FireWire disk, a CD-ROM drive, or another partition or disk inside the computer.
The Open Firmware Password Application is available from Apple.