I'm talking about being able to call into Go code comprising a shared library via some sort of C calling convention. What you're referring to is something almost any modern language can do, which is call a C library via some sort of library loading mechanism (ctypes, FFI, etc.).

You can see a recent proposal for shared library support in Go and some reactions here:

https://groups.google.com/forum/#!topic/golang-nuts/zmjXkGrE...

So unless what you're talking about has happened in the past few months, I'm not aware of true shared library support in Go.

Practically speaking, shared library support is absolutely necessary if you're looking to use a low-level language as a means of speeding up a dynamic language. Or least highly-desirable (you can use IPC, but you lose a lot of speed, which is often the reason why you're using the lower-level language in the first place).