We've been using Go in production on our proprietary email platform for a couple years now for daemon services, web APIs and EMR jobs[1]. A few other teams have also picked up the language and are building out new systems to support comments, mobile and I think a maybe a few other pieces of the site.
Go is definitely not our only tool in the box and many teams (including mine) still use Python, C++ or whatever works best for the job at hand, but I think there definitely is a trend of Go being the choice for a lot of new server side systems.
Our CTO made our first post to Medium explaining the move: https://open.nytimes.com/introducing-the-new-open-blog-23eba...