You can't really get hardware accelerated antialiasing on the PS2 :p. Developers who want it would have to do it in software, which consumes way too much resources compared to the results :p. A shame really, even the Dreamcast had antialiasing.

It's not really the same as texture filtering at all, though. Antialiasing smoothens the edges of polygons, while texture filtering smoothens the textures that are applied to a surface. Both can usually be turned on and off independently of the other, that is, as long as the graphics engine supports the features.