If your wondering what this was...
here it is:
The next system software update for the PlayStation 3 (PS3) system will be released on April 1, 2010 (JST), and will disable the “Install Other OS” feature that was available on the PS3 systems prior to the current slimmer models, launched in September 2009. This feature enabled users to install an operating system, but due to security concerns, Sony Computer Entertainment will remove the functionality through the 3.21 system software update.
In addition, disabling the “Other OS” feature will help ensure that PS3 owners will continue to have access to the broad range of gaming and entertainment content from SCE and its content partners on a more secure system.
Consumers and organizations that currently use the “Other OS” feature can choose not to upgrade their PS3 systems, although the following features will no longer be available;
* Ability to sign in to PlayStation Network and use network features that require signing in to PlayStation Network, such as online features of PS3 games and chat
* Playback of PS3 software titles or Blu-ray Disc videos that require PS3 system software version 3.21 or later
* Playback of copyright-protected videos that are stored on a media server (when DTCP-IP is enabled under Settings)
* Use of new features and improvements that are available on PS3 system software 3.21 or later
For those PS3 users who are currently using the “Other OS” feature but choose to install the system software update, to avoid data loss they first need to back-up any data stored within the hard drive partition used by the “Other OS,” as they will not be able to access that data following the update.
Subject: version 3.21 
Wed Apr 14, 2010 8:52 am
