It went like this: PlayStation, PlayStation2, PlayStationPortable, PlayStation3, and soon- PlayStation4. The original. Seriously... You don't hear about the original being called '1' in the name.
By the way, I've had both the PS and PS2, games on those are way better (atleast based on story and character development, not aesthetically) than on the PS3 and everything we have today. (XBox 360 has its own games, PS3 is just re-using old characters [R&C] and ruining them).