Is Go programming language production ready?

Has it been used in any large production environments besides Google?

Yes, Go is production ready.

I would especially recommend using Go for projects for which the language and its extensive standard library are sufficient out of the box. For other projects I would decide case by case, but would prefer Go to any other compiled language.

I don't know about large production environments using Go besides Google and the Google App Engine. There are many smaller organizations using it for production code though.

Bruce Eckel has some very interesting things to say about Go Bruce Eckel on Go