100% behind you on this, crawshaw. Although I've never missed having a Python style REPL for golang ("go run" usually fits the bill). You make a convincing argument for why it would indeed be a very powerful tool for any Linux admin's toolbox ;)
It's premature for feature requests I know. But I'd love to be able to view the Stack Trace of a live running goroutine. Typically something I log to disk using the "runtime" calls. To be able to probe that info from a command shell would be neat, don't you think?