Sony has offered the Other OS feature on the original "fat" PS3 consoles since the units launched years ago. When the new PS3 Slim came around the feature was axed.
Sony has announced that the newest update for the PS3 that is set to hit on April 1 will eliminate the Other OS feature. Most of us don't use the Other OS feature but if you do this is bad news.
Sony says the elimination is due to security concerns. If you want to keep the feature, your only recourse is to not upgrade ever again. You will need to back up the data on your Other OS partition if you do update since it will not be accessible after.