From the FAQ :
What is the purpose of the project?
[...] By its design, Go offers an approach to building system software on multicore machines.
Is Google using Go internal?
The Go project was conceived to simplify work with servers and other software that uses Google internally, but the implementation is not mature enough, but for widespread use. As we continue to develop, we are also experimenting with the language as a candidate medium. He got there. For example, the server http://golang.org is a Go program; in fact, it is just a godoc document server running in a production configuration.
Thus, the proposed domain is the development of systems and servers for existing multicore machines.