Our advice on approach for currently so called "mobile optimisation" is to use responsive technique for different screen size, not separate domains for different device. That's the simple rule we always follow.

Using a separate domain option should be kept for optimization of the content to different regions.

Yes, we do responsive layout and it's adaptive and fluid. Our Onxshop CMS is fully responsive in the backend and all our clients now have the option to turn their websites into responsive by simply adding this line into their CSS:

@import url(/share/css/default/theme_layout/responsive.css);

We have also built layout examples and it's now default template on http://cloud.onxshop.com/

Go there an have a try! Happy windows resizing!