Aside from pulling newer firmwares via it’s software interface (the XMB), the PlayStation can also be updated via USB.

Requirements:

• An unused USB drive (or any storage device than can be connected via USB)
• The update you want to install

Important Note:

Do note that you can’t downgrade your PS3 this way.  The firmware will only be installable if and when the firmware version you’re going to install is higher than the firmware your PlayStation 3 is currently on.

How to install a PS3 firmware update via a USB key?

• Prepare your storage device by formatting it as Fat32 and creating the following directory( X:/PS3/UPDATE)
  • If you’re not sure how to do this, on your storage device continue reading, if not, skip to the next step
  • Create a PS3 folder on your chosen storage device and within it, create another folder called UPDATE
• Download the update you need to install.  This is a .pup file.  If it’s a zip file, you’ll need to extract it.
• Copy the .pup file onto the update folder you’ve created in your storage device
• Make sure your PS3 is turned off.
• Connect your storage device to your PS3
• Once connected your PS3 detects the USB device, go to Settings > System Update > update via Storage Media
• Select the storage media connected to the PS3 and install the new firmware
• And done