The chaps over at PC Watch (in Japanese) got their hands on a PS3 and promptly took it apart. When I say took it apart, I mean they went as far as removing the heatspreader from the GPU! Check out the pictures ;)

In other news, ps3.qj.net claims it only takes four easy steps to install another system software on the hard disk of your PS3. Not only can you swap 2.5" SATA HDD, you can change the operating system (OS) software. Of course, you need compatible third-party software. The official www.playstation.com just says "details will be posted soon", but  they have some info how you'd do it:

- Do not turn off the PS3 system or remove the disc or storage media during installation. Doing so may cause damage to the system software.
- During installation, the power button on the system front is inactive. [We're guessing this means: In other words, don't panic, and don't get confused. Your system is on and busy - don't turn it off!!!!!]

1. Insert the disc or storage media that contains the installer in the system.
2. Select (System Settings) under (Settings) in the home menu.
3. Select [Install Other OS]. The system searches for the installer. When the installer is found, its content and location will be displayed.
4. Check the content of the installer, and then select [OK]. The installer starts. Follow the on-screen instructions to complete the operation.

Sony even offers hints. Wow! It's like they want us to try different OS! They keep showing how gamer-centric they are.

- To start the newly installed system software, go to (Settings) > (System Settings) > [Default System], and then select [Other OS] to restart the system.
- An appropriate USB adaptor (not included) is required to use storage media with some models.

Update: Here's a four part video of the complete disassembly of a PS3.