I'm surprised that people haven't commented on the implicit story here: the intention to deliver the "Shiny" cross-platform graphical toolkit for Go. If that happens, Go becomes one of the very few programming languages with a default cross-platform UI library.
> very few programming languages You mean apart from Tcl, Python, Java, Factor, just about every Smalltalk apart from GNU Smalltalk, Racket, possibly Ruby…
No, there really aren't that many. Even fewer that are "professionally" usable. (I am not committing to Go's toolkit joining that latter set as I've not yet seen or used it.)