There are quite a few things you need do to differently in order to write a great Windows 8 App. Although MSDN has it documented completely in their site, the sheer volume of other related information might overwhelm you.
In order to make it easy, they have a single pdf with all the relevant information. The file will also serve as a ‘quick ref’ document whether you are developing using C#-XAML or HTML5-JS-CSS or C++-DirectX style.
And yes, this has been updated for the RTM version.