The PlayStation 3 is able to run another operating system in addition to the XMB. To install the bootloader for another OS, you must obtain the “otheros” installer and install it via the Settings menu: [Settings] > [System Settings] > [Install OtherOS]. OtherOS installations are not supported on the PlayStation 3 Slim model (PS3-2000).
Warning: Only attempt this if you know what you are doing. Only a limited number of operating systems will work on the PS3: Fedora Core Linux (5, 6 and 7) and Yellow Dog Linux 5 are just two examples.