The Microsoft Surface will be running Windows RT, and is based on ARM architecture. This is different to the desktop version of Windows 8, by virtue of not having a full desktop mode, apart from accessing the File Explorer and the complementary "RT" versions of the Microsoft Office Applications.
During the press event where the Surface was presented, which we reported on, Microsoft also confirmed that the Surface Pro will be released 90 days after the ARM-based Surface. The Surface Pro will be based on Intel Core Ivy Bridge architecture and will be running the full version of Windows 8. The SEC filing mentioned above gave no details of the Surface Pro, and so we presume that the 90 day delay of the Surface Pro has not changed.
You can read more about the Surface and Surface Pro in our original report.