A Theory Why we get Only One Button
Via Slashdot: Andru at GearLive writes about Apple's one button mouse. Lots of interesting comments there, too.
While I'm not sure that's really Apple's rationale, it certainly is one of the better explanations I've heard so far. Even though I wrote in My Ideal OS Article why I think the scroll wheel solves the problem of accidentally clicking the wrong button, I didn't really think about the fact that it muddles down the illusion that the mouse is your hand.
You point at things, you push buttons, and you pick up and drag around things on the screen. You'd be very surprised if you had a button on your CD player that did something different depending on what finger you used to push it, and that's essentially what two mouse buttons equate to in the current metaphor.
OTOH, it might be a better fit for mouse gestures. After all, there are many gestures in real live whose meaning completely changes if you use a different finger ;-)