You guys are reading the branding wrong.
These are branded under 'Surface', or 'Microsoft Surface' in long form. Surface is a family of personal computers for Windows 8.
There are 2 models:
-Surface for Windows RT.
-Surface for Windows 8 Pro.
I'm not sure if these are final, but let's fucking hope not. I think the confusion comes from Microsoft's use of the word 'Windows', as if it's a cohesive single OS. It's not, they've radically branched it off into two architectures that don't play with each other and that distinction should be reflected in the brand.
Source:
http://www.microsoft.com/en-us/news/press/2012/jun12/06-18announce.aspx