Great info here: Mobile Sites vs. Apps: The Coming Strategy Shift from Jakob Nielsen's Alertbox - especially about responsive design as a tool but not the solution.
I hear a lot of talk about a single web site using responsive design being able to effectively service computer, tablet and mobile visitors. Maybe for simple sites this approach would work, but I don't think it can be as effective as a dedicated design for mobile or even a mobile "app".
Like any new trend, the short term impact of responsive design is overestimated, while the long-term impact is underestimated. This comes down to overusing it as a solution - a common trend in technology.
Content management systems will need to support different elements and tweaks for mobile. Designs and layout can be smart, just not that smart.