We're using it for all our toolchain in our small first game. We've also created a small build system based on v8 (javascript), but integrated it using go, it generates all your project so you just need to compile it.

We were using it also for our web page (a custom blog engine made on go), but, we left it on alpha, and Go 1 changed a lot, gofix didn't fixed and priorities made us choose another tool for our web page.

Still, i think go only needs a desktop GUI toolkit to become popular. It has a lot of potential.