I have used an iPhone and the scrolling is smoother - big deal.

Would I complain about it - no it just not that important.

Would I base a buying decision on that? No.

I like the hardware of the iPhone - it's very nice.

Capacitive vs resistive argument is plain dumb.

They are just different technologies.
Capacitive screens are nice if accuracy is not important, multi-touch is nice and of course you can have a solid screen (e.g. glass).
Resistive screens allow you to use a stylus, have more accurate control and the screen needs some "flex" in-order for it to work.

Both technolgies have their uses.

iPhone is more an entertainment product and the n900 is probably more practical.

I don't think the scroll speed is tied to the touch-screen technology - it's probably more to do with OS design e.g.The n900 is multi-task system and the iPhone is "single-task".