I am working on a new protocol in my research which needs to take these issues into account and I am gradually thinking my way around to the best way to do it (hopefully).
Accessibility refers to the ability [of web content] to be accessed by everyone, regardless of their abilities or the device they are using. In the past this has meant things like using ALT tags, providing text based navigation, and so on. Guidelines for accessibility are developed by the W3C Accessibility Initiative.
I talked to Liddy Nevile recently about accessibility and she says it is turning into adaptivity instead…that is, sensitivity to the user and their capabilities at a moment in time.
I would (and I realize this is terribly geeky), rather than thinking of devices and users separately, probably think of a unified approach, where we think of the user as having a set of capabilities, just like a Palm…Content Selection for User Independence. Or, in my view, Content Selection for User Preferences. That is, personalized rather than vanilla.
Now my head hurts, but I am getting somewhere.