the 80GB PS3 from the MGS4 bundle was the last version that has PS2 backward compatibility. OpenPS2Loader also works for 80GB PS3 mentioned above.
the slim PS3 isn't totally useless. the slim is like 32-33% both lighter and smaller from it's predecessor. the console also runs quieter and cooler (helps in dealing with ylod issue). minor hardware peripherals have been removed (as in a 2nd OS install feature). besides, linux wasn't very fast and installing it isn't easy either.
60GB console enthusiasts get the best of extra features including PS2 gameplay but they'll have to compromise with older hardware flaws while the slim users enjoy a more refined console with less flaws. .
PS1/SCPH-7501 | MM3 modchip
PS2 v9 | 250GB hdd | PS3 component cable | katana 32mb mc
PS3/CECH-2001B | 250GB hdd | 3.65 ofw