Google has added social profiles and icons to the local knowledge graph. This was discovered by @ryanbowlerhat and Joy Hawkins posted this on Twitter. Joy is a super focused local SEO who tracks this stuff and she confirmed with me that previously only big brands had social profile icons but now even small brands will show social icons, if they have it, in the local knowledge graph.

Here is a screen shot:

I was not sure if it was new, but Joy is confident it is:

Forum discussion at Twitter.