I came here to post just this. Bret Taylor, one of the co-founders of FriendFeed, was CTO @ Facebook after the acquisition.

Also besides FBSON, most of what I've read in those slides looks like PostgreSQL's JSON support:

[1]: JSON type http://www.postgresql.org/docs/9.4/static/datatype-json.html

[2]: JSON functions http://www.postgresql.org/docs/9.4/static/functions-json.htm...