Where to Start [with RWD] by Trent Walton
“If a team is knee-deep in .PSDs before considering layout changes and alternate viewports, opportunities for optimization and innovation will be overlooked. I’d rather proactively embrace a new approach than try to shoehorn an old one.”
For nearly two years now, I've been knuckle-deep in Responsive Web Design. Everything Trent says in this article is spot on & I couldn't have said it better myself. If you're building sites on the web, read this article right now.