The demos you mention use the Modern theme to which we have applied a bit or restyling. The rest is binding the metro theme colors to different values to achieve the final result. A good article on the subject is this one:
Also I suggest you download the source code of the demos (available under your account) to get the restyled controls. Please note that not all controls are styled and some of the bigger controls are styled partially to fit this specific scenario.
That said I will discuss the possibility of extending these designs to a full theme though I cannot make any promises of actual implementation.
the Telerik team