According to Sony in their latest PlayStation Blog entry, firmware version 3.21 will be released on April 1st. Included with this update is the removal of the "Install Other OS" option on the PS3 system.
The reasoning behind disabling the ability to install another OS was due to "security reasons" which most likely involve hacking the PS3 system in order to play pirated games.
For those who use Linux on their PS3, Sony has left the option not to upgrade to the latest firmware, but in turn all access to the PlayStation Network, movie and game playback, and further updates will be disabled for the system.
Even though this is a precautionary step for Sony, it may be a bit of a step in the wrong direction to protect against piracy. Then again, fighting piracy and keeping people happy has never been easy for Sony.
Source: PlayStation Blog