Sony is releasing Firmware 3.21 for older PS3 models this Thursday, April 1st and with the update, users are loosing the option to "install other OS."
If users do not upgrade to the new firmare to be able to keep a version of Linux running on their PS3 will not be able to access PlayStation Network and thus, loosing the ability to play games online.

[...] users to install and use a Linux OS, option in the PlayStation 3. The feature was removed in a recent firmware upgrade, which was released in early [...]
[...] released PlayStation firmware 3.21 for older PS3 models earlier this month and when users upgrade, they loose the ability to have a [...]