Neowin reports that according to a known computer security researcher, Microsoft's SmartScreen feature implemented in Windows 8 reports information to Microsoft about every application installed

The issue with SmartScreen is currently only prevalent in Windows 8 as it's the first time Microsoft has integrated SmartScreen at an OS level (Windows 7 only features SmartScreen in applications like Internet Explorer). You can disable SmartScreen so you are no longer reporting your installation habits to Microsoft, but this is apparently not easy to do and results in periodic nags to re-enable it.

Chances are Microsoft will not do anything about their implementation of SmartScreen, so as it stands now it could be a privacy and security risk.

  Windows 8 tells Microsoft about everything you install