Search results in Windows 8.1 combine local searches with results from the Bing search engine. For some users this might pose privacy / security issues.
In the Windows 8.1 Preview the Search Suggestions and Web Results from Bing feature is easily disabled (and I assume that this will be the same for 8.1 upon release).
Press the Windows key and C together to bring up the charms bar (or swipe from the right on a touch device). Click Change PC Settings:
Click Search & apps in the left hand pane:
Toggle the Get search suggestions and web results from Bing to the Off position.
Search results now do not include results from Bing: