Accessibility is much about understanding what can be perceived and understood. Yes, non-tactile buttons aren't great for people who rely on touch - but that doesn't matter if there's a better interface that is accessible.

A visual person looks at an iphone and sees the touch screen as a series of hotspots, something akin to a button. But, it's a flat surface, it doesn't have to be interpreted as non-tactile buttons.

Look at an iphone touchscreen when the phone is switched off. Now look at a Macbook touchpad. If the touchpad - with no 'screen' behind it, or no display at all - how would you use that to navigate around the various features of an iPhone like OS?

Very quickly you'd land on the idea of gestures with spoken output. You'd create a navigation of gestures. Swipe left to move to the next application. Swipe right for the previous application. Double tap to activate the selected application. That's just for starters.

As the iphone demonstrates, there's a rich language for interacting with the device that seems to be enough to navigate around the various features of the phone.

Accessibility is about providing the equivalent functionality. No-one ever said the way of using it had to be the same, just equivalent. A different interaction allows access to the same functionality.

I remain deeply impressed with Apple for producing a mobile device that for the blind community absolutely rocks. It's a pity that Google's equivalent device is not as well thought out or implemented, sure it works for TV Raman, but others I've spoken to have concluded that Google's attempts are nowhere near iPhone quality.

I recently made the mistake of buying a Cowon touchscreen media player to use as portable music player. It had no control buttons apart from very bad volume buttons so i could not control it "blindly" when it was in my pocket. Sold it weeks later to get a proper player.