Google has officially confirmed of experimenting "Sources" in its search results. First, spotted by Cyrus Shepard notes on his Google+ post - "These only seem to appear for certain queries. It looks like an attempt at filling in the empty space on the right hand side of the screen when no ads appear."
Adding he says, "The "sources" contain background information about the query, such as definitions, company information, recent news, etc. When I queried Twitter, it returned a Wikipedia entry, info on the CEO, headquarter location, what language the application is written in (Ruby) and so forth."
"There's also a strange field that says: "Name: Sign In" - Is that supposed to be my name, or a semantic person field populated by Twitter? Regardless, more confusion. It also says the category is "Private." When I click on Private, I'm taken to a SERPs for the word "private." Not helpful," added Shepard.
A Google spokesperson confirms to SEL stating "Google is constantly experimenting with new features" statement.
Shepard, shared a couple of screenshots of the new 'Source" display including: