I believe they had to jailbreak these to get Linux installed on them.

OtherOS was a fully supported feature on the PS3, that enabled you to install Linux on a secondary partition on the built in HDD. At least until George Hotz used it to get hypervisor access and exploit the PS3.

This lead to the feature being removed and him being sued by Sony.

https://en.wikipedia.org/wiki/George_Hotz#Sony_lawsuit