Yeah, I'm still using CS1 at home on my PowerBook.
If I had an Intel machine, I'd want CS3 just for the full, optimal compatibility and so that things aren't running in emulation or whatever. I may or may not actually
notice it, but, in my mind, I'd feel better about it all. I'd
feel like things are running and working at their fullest, and I just like that. It's comforting.
When I finally upgrade to a new Mac, I'll also be upgrading my Adobe CS software (or, at the very least, the CS3 Illustrator since that's all I really want to use or pursue freelance work with at this point). But it's less for the features (I'm not someone who gloms on to the latest marquee features and wears them out anyway) than for the native Intel compatibility. But that's just me...