Last time I checked this was the main thing that was missing for Go (a complete, multi platform GUI lib). Has there anything like this arisen yet? Some quick googling points to Gothic, which sounds promising.
Go I suspect is intended for more service related stuff, backend, server, processing, etc.
Though I'm not 100% sure about this.
The good side of it, is that you can also bind a web rendering engine totally coded in Go or bind the webkit rendering to the compositor backend..
I hope i get there soon..