The update fixes the sound clipping and sound lagging in PS1 games, while running in Full display.
[quote name='Chitown021']Man, having to plug the PS3 controller into the USB port to update annoys the crap out of me. Do they do that to make sure the controller doesn't run out of juice mid update??[/QUOTE]Actually, that's basically the same question as why can't you run AIM/MSN while installing an update? The reason is that many of the firmware updates reconfigure, make changes, additions, etc. to the bluetooth device on the PS3. While the PS3 is installing the update, controllers need to be plugged into a USB port so the update can take place (so bluetooth isn't being used). If the controllers were being used while the bluetooth is having an update installed, you're just asking for problems (kind of like running AIM and installing an update). Then again, part of the reason too is that for the controllers don't run out of batteries (because if your controller dies while updating and cannot select the option to restart, you're just asking to brick your PS3). The PSP asks for the battery to be plugged in so you don't brick it while installing an update.