> Embed javascript as a scripting language into a Go app.
Sure, but you could already do that. There are several V8 implementations in Go you could use directly to invoke javascript code, but you'd have to pass values directly in and get return values directly out to interface between the two languages.
Build bindings to system functions in Go (e.g. write the common parts of an app in JS, run it in V8, write platform-specific things in Go).
Write the next Node.js/Io.js in Go?