If you’re thinking about changing your WordPress theme to a responsive one, this infographic from WhoIsHostingThis makes things easy.
Basically one theme can adjust to any screen and screen ratio. There is no need to plugins that detect mobile browsers and pull a mobile style sheet to be used.
One of the best responsive WordPress themes is Pinboard by Daniel Tara. Go to link, click on a Preview button, and resize the browser window to see how the layout responds to different width.
Via Website Magazine.