Within a few years, mobile use is going to outpace desktop use. The only practical solution I see at this point for dealing with the proliferation of different screen sizes and devices is responsive design.
"Code, content and Presentation" seems like a likely place for responsive design, but I think that minimizes the eventual importance of the concept.
I've been working with screen width rather than individual devices. Portrait/landscape changes alter the width, which seems like a better working variable to me.