This is a topic I've kinda covered here before, and it is certainly a topic I think will have many different opinions (and will change over time), but what do people think about the question below?
Can you recommend a best approach or best practice for developing a website for multiple devices? Should I try to detect screen sizes and basically have two or three sets of pages each dedicated to a range of display sizes. Or should I instead use the CSS approach? I predict that prevailing wisdom with say CSS but I tend to want to use the first approach.
Personally my gut tells me that while CSS allows us to gracefully handle desktop versus mobile (at least sometimes), it doesn't always make sense for a mobile site to mimic a desktop site. For example, a RIA like a site administrator might not make sense to have 1-1 feature equality on mobile. There are some tasks I can't imagine needing or wanting to do on a mobile device. So I'd rather the mobile application focus on a subset of things that make sense to do on a phone versus trying to fit everything in. On the flip side, I fully expect simple content sites, like blogs, to have the same feature set on desktop versus mobile.
In other words - I would not automatically try to force the exact same site onto other devices - possible or not.