No, it works a little differently for the Playstation 3. If you have a 60 gb hard drive, I believe it shows as 50/55 or somewhere around there. The file system is a custom made, possibly FAT32 based proprietary from Sony, which it turns out is actually pretty wasteful with space. Again, I have a 120gb hard drive, and when put into the Playstation 3, it shows up as 111gb, but I only get around 80-90 gbs of that being useable. That's
WITHOUT a Linux partition set up. As for 20gb's having no space, I told you the Playstation 3 takes a certain percentage of the hard drive, I believe it was like 5% or so. So if you have a smaller hard drive, It would take less space, than with a bigger drive. Essentially, the bigger the drive, the more wasted space. There's a huge thread on the Official Playstation forums on this topic, though it might be burried...Just do some digging
Edit:
Here's some posts
http://boardsus.playstation.com/playstation/board/message?board.id=ps3&thread.id=2738113&view=by_date_ascending&page=1http://boardsus.playstation.com/playstation/board/message?board.id=ps3&thread.id=1587166&view=by_date_ascending&page=1http://boardsus.playstation.com/playstation/board/message?board.id=ps3&thread.id=2926845&view=by_date_ascending&page=1Also, this was pulled from the Unofficial Playstation 3 Faq:
http://boardsus.playstation.com/playstation/board/message?board.id=ps3&thread.id=1963427My Hard Disk Drive Appears To Not Have As Much Space As Advertised!
a few reasons cause this effect:
1. Manufacturers calculate drive size as 1 gigabyte as (10^9) not as (2^30)
1. Consumer confusion caused by non standard units of measure
2. PS3 internally uses 2^30, Manufactors of Drives use 10^9
2. Firmware - while stored and used mostly in flash memory - has a backup copy on the HDD
3. Swap File that is approximately 10% of drive size (80 gig... 7 gig swap file)
4. Future System Updates reserved space
1, 2, 3 are confirmed 4 is supposition.
Hope this helps!