I recently acquired a 60GB PS3 to go along with my 80GB. I want to use the 60GB as my main unit to clear up the PS2 spot (I've got a memory card adapter, etc already).
I'm still working on it, and am not finished as I got swamped doing a hard drive recovery on a customer computer all through the night.
I decided to make a list of findings in trying to swap drives:
1. You cannot swap drives directly. Each drive, when formatted I assume, links itself to the unit it is in.
2. Different PS3 models have different HD caddies, (though I cannot tell the differences exactly) my 80gb goes in SATA-port first, whereas the 60GB goes in 90 degrees from that and then slides to the side (don't lose that blue screw!)
3. Backups can only be made onto a FAT32 partition.
4. When you put any drive that is not linked with a PS3 into that PS3, it will ask to format upon booting.
5. When I placed one of the drives into the other unit, despite making sure both machines were on firmware 2.8, it asked for the update file and went through some crap before it would format the disk inside. This confused me.
6. If you want to keep your Trophies, hit triangle on your trophies and upload that data to Sony BEFORE you format anything, as they WILL NOT be copied into a backup.
7. Using the backup function (under System settings) and copying to ANOTHER PS3 did not transfer my saved games or installed game data or downloaded games/demos. You will need to transfer your saved games separately (by copying them individually to your external storage media, one-by-one as there is no "copy all" function), and then copy them into the new drive. I have also heard that some saves may not function on the new unit, I do know one of mine refused to copy (Lost Planet?).
8. You can easily re-download purchased items off of PSN, but you can only have a game installed on five units at the same time, so look into deactivating an old install if possible/necessary.
9. Many of your user settings will not get copied, such as your theme. None of the system settings will copy either, such as your wireless/network settings.
10. My user profiles, when copied to the new machine, have an asterisk (*) next to them. I do not know what this means.
Feel free to make suggestions, explainations (especially!) and additions. I want this to be a semi-comprehensive list as I haven't found but bits and pieces of information all over the net that are not consolidated into an easy-to-access form.