Most people have never used the scroll wheel. They move their mouse to the down arrow on scroll bar and click.

I wonder how true this is, with the scroll wheel having been around for the last ten years or so.

Nevertheless, if these folks do exist, they're in for a sore surprise if they upgrade to Lion.

Well considering that Macs are still a small percentage of PCs and that Macs don't have scroll wheels I don't think most people will notice.

Mac(Book)s (and Macs with the magic apple mouse) have two finger scroll which is the same thing, but isn't supported (but should be, please!) on say the headline box in the Skimmer "Spread" layout.

They are almost the same thing. They perform the same function but because they are physical invisible they are even less likely to be used by an average computer user.

I have some anecdotal evidence on the contrary. My wife is a very casual computer user, but uses two-finger scroll all the time. My sister-in-law is very similar - not a computer person, but has an Apple laptop and uses two-finger scroll. Also, Apple mice support scrolling[1], and almost any third-party mouse you buy will have a scroll button as well. Scrolling with a mouse or trackpad seems like an integral part of user interaction.

[1] http://store.apple.com/us/product/MB829LL/A?fnode=MTY1NDA1Mg...

And every Mac user I know is well aware that for the web, <space> scrolls a page forward, <shift-space> a page back. So still no good argument for on-page controls.

Counterpoint: I didn't find out about shift-space until just now.

Counter-counterpoint: I didn't know you until just now :)

Wooah! Citation please??